Oro-pillow cushion assembly

ABSTRACT

A patient interface including a seal-forming structure having a mouth portion that forms at least part of the mouth plenum and is configured to seal around the patient&#39;s mouth and a nasal portion that is configured to seal with the patient&#39;s nares. The patient interface further includes a vent structure with a main body that is configured to be secured to the mouth portion and includes a vent wall with a plurality of vent holes, a receptacle, and a pair of anchor sockets located on opposing lateral sides of the receptacle. A cover for the vent includes a pair of anchor pegs on lateral sides of the cover. The anchor pegs are configured to be inserted into the anchor sockets to secure the cover to the main body. A diffuser is received within the receptacle between the anchor sockets and is sandwiched between the main body and the cover.

1 BACKGROUND OF THE TECHNOLOGY

This application is a continuation of U.S. application Ser. No.17/550,168, filed Dec. 14, 2021, now allowed.

1.1 FIELD OF THE TECHNOLOGY

The present technology relates to one or more of the screening,diagnosis, monitoring, treatment, prevention and amelioration ofrespiratory-related disorders. The present technology also relates tomedical devices or apparatus, and their use.

1.2 DESCRIPTION OF THE RELATED ART 1.2.1 Human Respiratory System andits Disorders

The respiratory system of the body facilitates gas exchange. The noseand mouth form the entrance to the airways of a patient.

The airways include a series of branching tubes, which become narrower,shorter and more numerous as they penetrate deeper into the lung. Theprime function of the lung is gas exchange, allowing oxygen to move fromthe inhaled air into the venous blood and carbon dioxide to move in theopposite direction. The trachea divides into right and left mainbronchi, which further divide eventually into terminal bronchioles. Thebronchi make up the conducting airways, and do not take part in gasexchange. Further divisions of the airways lead to the respiratorybronchioles, and eventually to the alveoli. The alveolated region of thelung is where the gas exchange takes place, and is referred to as therespiratory zone. See “Respiratory Physiology”, by John B. West,Lippincott Williams & Wilkins, 9th edition published 2012.

A range of respiratory disorders exist. Certain disorders may becharacterised by particular events, e.g. apneas, hypopneas, andhyperpneas.

Examples of respiratory disorders include Obstructive Sleep Apnea (OSA),Cheyne-Stokes Respiration (CSR), respiratory insufficiency, ObesityHyperventilation Syndrome (OHS), Chronic Obstructive Pulmonary Disease(COPD), Neuromuscular Disease (NMD) and Chest wall disorders.

Obstructive Sleep Apnea (OSA), a form of Sleep Disordered Breathing(SDB), is characterised by events including occlusion or obstruction ofthe upper air passage during sleep. It results from a combination of anabnormally small upper airway and the normal loss of muscle tone in theregion of the tongue, soft palate and posterior oropharyngeal wallduring sleep. The condition causes the affected patient to stopbreathing for periods typically of 30 to 120 seconds in duration,sometimes 200 to 300 times per night. It often causes excessive daytimesomnolence, and it may cause cardiovascular disease and brain damage.The syndrome is a common disorder, particularly in middle agedoverweight males, although a person affected may have no awareness ofthe problem. See U.S. Pat. No. 4,944,310 (Sullivan).

1.2.2 Therapies

Various respiratory therapies, such as Continuous Positive AirwayPressure (CPAP) therapy, Non-invasive ventilation (NIV), Invasiveventilation (IV), and High Flow Therapy (HFT) have been used to treatone or more of the above respiratory disorders.

1.2.2.1 Respiratory Pressure Therapies

Respiratory pressure therapy is the application of a supply of air to anentrance to the airways at a controlled target pressure that isnominally positive with respect to atmosphere throughout the patient'sbreathing cycle (in contrast to negative pressure therapies such as thetank ventilator or cuirass).

Continuous Positive Airway Pressure (CPAP) therapy has been used totreat Obstructive Sleep Apnea (OSA). The mechanism of action is thatcontinuous positive airway pressure acts as a pneumatic splint and mayprevent upper airway occlusion, such as by pushing the soft palate andtongue forward and away from the posterior oropharyngeal wall. Treatmentof OSA by CPAP therapy may be voluntary, and hence patients may electnot to comply with therapy if they find devices used to provide suchtherapy one or more of: uncomfortable, difficult to use, expensive andaesthetically unappealing.

Non-invasive ventilation (NIV) provides ventilatory support to a patientthrough the upper airways to assist the patient breathing and/ormaintain adequate oxygen levels in the body by doing some or all of thework of breathing. The ventilatory support is provided via anon-invasive patient interface. NIV has been used to treat CSR andrespiratory failure, in forms such as OHS, COPD, NMD and Chest Walldisorders. In some forms, the comfort and effectiveness of thesetherapies may be improved.

Invasive ventilation (IV) provides ventilatory support to patients thatare no longer able to effectively breathe themselves and may be providedusing a tracheostomy tube or endotracheal tube. In some forms, thecomfort and effectiveness of these therapies may be improved.

1.2.2.2 Flow Therapies

Not all respiratory therapies aim to deliver a prescribed therapeuticpressure. Some respiratory therapies aim to deliver a prescribedrespiratory volume, by delivering an inspiratory flow rate profile overa targeted duration, possibly superimposed on a positive baselinepressure. In other cases, the interface to the patient's airways is‘open’ (unsealed) and the respiratory therapy may only supplement thepatient's own spontaneous breathing with a flow of conditioned orenriched gas. In one example, High Flow therapy (HFT) is the provisionof a continuous, heated, humidified flow of air to an entrance to theairway through an unsealed or open patient interface at a “treatmentflow rate” that may be held approximately constant throughout therespiratory cycle. The treatment flow rate is nominally set to exceedthe patient's peak inspiratory flow rate. HFT has been used to treatOSA, CSR, respiratory failure, COPD, and other respiratory disorders.One mechanism of action is that the high flow rate of air at the airwayentrance improves ventilation efficiency by flushing, or washing out,expired CO2 from the patient's anatomical deadspace. Hence, HFT is thussometimes referred to as a deadspace therapy (DST). Other benefits mayinclude the elevated warmth and humidification (possibly of benefit insecretion management) and the potential for modest elevation of airwaypressures. As an alternative to constant flow rate, the treatment flowrate may follow a profile that varies over the respiratory cycle.

1.2.3 Respiratory Therapy Systems

These respiratory therapies may be provided by a respiratory therapysystem or device. Such systems and devices may also be used to screen,diagnose, or monitor a condition without treating it.

A respiratory therapy system may comprise a Respiratory Pressure TherapyDevice (RPT device), an air circuit, a humidifier, a patient interface,an oxygen source, and data management.

1.2.3.1 Patient Interface

A patient interface may be used to interface respiratory equipment toits wearer, for example by providing a flow of air to an entrance to theairways. The flow of air may be provided via a mask to the nose and/ormouth, a tube to the mouth or a tracheostomy tube to the trachea of apatient. Depending upon the therapy to be applied, the patient interfacemay form a seal, e.g., with a region of the patient's face, tofacilitate the delivery of gas at a pressure at sufficient variance withambient pressure to effect therapy, e.g., at a positive pressure ofabout 10 cmH₂O relative to ambient pressure. For other forms of therapy,such as the delivery of oxygen, the patient interface may not include aseal sufficient to facilitate delivery to the airways of a supply of gasat a positive pressure of about 10 cmH₂O. For flow therapies such asnasal HFT, the patient interface is configured to insufflate the naresbut specifically to avoid a complete seal. One example of such a patientinterface is a nasal cannula.

Certain other mask systems may be functionally unsuitable for thepresent field. For example, purely ornamental masks may be unable tomaintain a suitable pressure. Mask systems used for underwater swimmingor diving may be configured to guard against ingress of water from anexternal higher pressure, but not to maintain air internally at a higherpressure than ambient.

Certain masks may be clinically unfavourable for the present technologye.g. if they block airflow via the nose and only allow it via the mouth.

Certain masks may be uncomfortable or impractical for the presenttechnology if they require a patient to insert a portion of a maskstructure in their mouth to create and maintain a seal via their lips.

Certain masks may be impractical for use while sleeping, e.g. forsleeping while lying on one's side in bed with a head on a pillow.

The design of a patient interface presents a number of challenges. Theface has a complex three-dimensional shape. The size and shape of nosesand heads varies considerably between individuals. Since the headincludes bone, cartilage and soft tissue, different regions of the facerespond differently to mechanical forces. The jaw or mandible may moverelative to other bones of the skull. The whole head may move during thecourse of a period of respiratory therapy.

As a consequence of these challenges, some masks suffer from being oneor more of obtrusive, aesthetically undesirable, costly, poorly fitting,difficult to use, and uncomfortable especially when worn for longperiods of time or when a patient is unfamiliar with a system. Wronglysized masks can give rise to reduced compliance, reduced comfort andpoorer patient outcomes. Masks designed solely for aviators, masksdesigned as part of personal protection equipment (e.g. filter masks),SCUBA masks, or for the administration of anaesthetics may be tolerablefor their original application, but nevertheless such masks may beundesirably uncomfortable to be worn for extended periods of time, e.g.,several hours. This discomfort may lead to a reduction in patientcompliance with therapy. This is even more so if the mask is to be wornduring sleep.

CPAP therapy is highly effective to treat certain respiratory disorders,provided patients comply with therapy. If a mask is uncomfortable, ordifficult to use a patient may not comply with therapy. Since it isoften recommended that a patient regularly wash their mask, if a mask isdifficult to clean (e.g., difficult to assemble or disassemble),patients may not clean their mask and this may impact on patientcompliance.

While a mask for other applications (e.g. aviators) may not be suitablefor use in treating sleep disordered breathing, a mask designed for usein treating sleep disordered breathing may be suitable for otherapplications.

For these reasons, patient interfaces for delivery of CPAP during sleepform a distinct field.

1.2.3.1.1 Seal-Forming Structure

Patient interfaces may include a seal-forming structure. Since it is indirect contact with the patient's face, the shape and configuration ofthe seal-forming structure can have a direct impact the effectivenessand comfort of the patient interface.

A patient interface may be partly characterised according to the designintent of where the seal-forming structure is to engage with the face inuse. In one form of patient interface, a seal-forming structure maycomprise a first sub-portion to form a seal around the left naris and asecond sub-portion to form a seal around the right naris. In one form ofpatient interface, a seal-forming structure may comprise a singleelement that surrounds both nares in use. Such single element may bedesigned to for example overlay an upper lip region and a nasal bridgeregion of a face. In one form of patient interface a seal-formingstructure may comprise an element that surrounds a mouth region in use,e.g. by forming a seal on a lower lip region of a face. In one form ofpatient interface, a seal-forming structure may comprise a singleelement that surrounds both nares and a mouth region in use. Thesedifferent types of patient interfaces may be known by a variety of namesby their manufacturer including nasal masks, full-face masks, nasalpillows, nasal puffs and oro-nasal masks.

A seal-forming structure that may be effective in one region of apatient's face may be inappropriate in another region, e.g. because ofthe different shape, structure, variability and sensitivity regions ofthe patient's face. For example, a seal on swimming goggles thatoverlays a patient's forehead may not be appropriate to use on apatient's nose.

Certain seal-forming structures may be designed for mass manufacturesuch that one design fit and be comfortable and effective for a widerange of different face shapes and sizes. To the extent to which thereis a mismatch between the shape of the patient's face, and theseal-forming structure of the mass-manufactured patient interface, oneor both must adapt in order for a seal to form.

One type of seal-forming structure extends around the periphery of thepatient interface, and is intended to seal against the patient's facewhen force is applied to the patient interface with the seal-formingstructure in confronting engagement with the patient's face. Theseal-forming structure may include an air or fluid filled cushion, or amoulded or formed surface of a resilient seal element made of anelastomer such as a rubber. With this type of seal-forming structure, ifthe fit is not adequate, there will be gaps between the seal-formingstructure and the face, and additional force will be required to forcethe patient interface against the face in order to achieve a seal.

Another type of seal-forming structure incorporates a flap seal of thinmaterial positioned about the periphery of the mask so as to provide aself-sealing action against the face of the patient when positivepressure is applied within the mask. Like the previous style of sealforming portion, if the match between the face and the mask is not good,additional force may be required to achieve a seal, or the mask mayleak. Furthermore, if the shape of the seal-forming structure does notmatch that of the patient, it may crease or buckle in use, giving riseto leaks.

Another type of seal-forming structure may comprise a friction-fitelement, e.g. for insertion into a naris, however some patients findthese uncomfortable.

Another form of seal-forming structure may use adhesive to achieve aseal. Some patients may find it inconvenient to constantly apply andremove an adhesive to their face.

A range of patient interface seal-forming structure technologies aredisclosed in the following patent applications, assigned to ResMedLimited: WO 98/004310; WO 2006/074513; WO 2010/135785.

One form of nasal pillow is found in the Adam Circuit manufactured byPuritan Bennett. Another nasal pillow, or nasal puff is the subject ofU.S. Pat. No. 4,782,832 (Trimble et al.), assigned to Puritan-BennettCorporation.

ResMed Limited has manufactured the following products that incorporatenasal pillows: SWIFT™ nasal pillows mask, SWIFT™ II nasal pillows mask,SWIFT™ LT nasal pillows mask, SWIFT™ FX nasal pillows mask and MIRAGELIBERTY™ full-face mask. The following patent applications, assigned toResMed Limited, describe examples of nasal pillows masks: InternationalPatent Application WO2004/073,778 (describing amongst other thingsaspects of the ResMed Limited SWIFT™ nasal pillows), US PatentApplication 2009/0044808 (describing amongst other things aspects of theResMed Limited SWIFT™ LT nasal pillows); International PatentApplications WO 2005/063328 and WO 2006/130903 (describing amongst otherthings aspects of the ResMed Limited MIRAGE LIBERTY™ full-face mask);International Patent Application WO 2009/052560 (describing amongstother things aspects of the ResMed Limited SWIFT™ FX nasal pillows).

1.2.3.1.2 Positioning and Stabilising

A seal-forming structure of a patient interface used for positive airpressure therapy is subject to the corresponding force of the airpressure to disrupt a seal. Thus a variety of techniques have been usedto position the seal-forming structure, and to maintain it in sealingrelation with the appropriate portion of the face.

One technique is the use of adhesives. See for example US PatentApplication Publication No. US 2010/0000534. However, the use ofadhesives may be uncomfortable for some.

Another technique is the use of one or more straps and/or stabilisingharnesses. Many such harnesses suffer from being one or more ofill-fitting, bulky, uncomfortable and awkward to use.

1.2.3.2 Respiratory Pressure Therapy (RPT) Device

A respiratory pressure therapy (RPT) device may be used individually oras part of a system to deliver one or more of a number of therapiesdescribed above, such as by operating the device to generate a flow ofair for delivery to an interface to the airways. The flow of air may bepressure-controlled (for respiratory pressure therapies) orflow-controlled (for flow therapies such as HFT). Thus RPT devices mayalso act as flow therapy devices. Examples of RPT devices include a CPAPdevice and a ventilator.

1.2.3.3 Air Circuit

An air circuit is a conduit or a tube constructed and arranged to allow,in use, a flow of air to travel between two components of a respiratorytherapy system such as the RPT device and the patient interface. In somecases, there may be separate limbs of the air circuit for inhalation andexhalation. In other cases, a single limb air circuit is used for bothinhalation and exhalation.

1.2.3.4 Humidifier

Delivery of a flow of air without humidification may cause drying ofairways. The use of a humidifier with an RPT device and the patientinterface produces humidified gas that minimizes drying of the nasalmucosa and increases patient airway comfort. In addition, in coolerclimates, warm air applied generally to the face area in and about thepatient interface is more comfortable than cold air.

1.2.3.5 Vent Technologies

Some forms of treatment systems may include a vent to allow the washoutof exhaled carbon dioxide. The vent may allow a flow of gas from aninterior space of a patient interface, e.g., the plenum chamber, to anexterior of the patient interface, e.g., to ambient.

The vent may comprise an orifice and gas may flow through the orifice inuse of the mask. Many such vents are noisy. Others may become blocked inuse and thus provide insufficient washout. Some vents may be disruptiveof the sleep of a bed partner 1100 of the patient 1000, e.g. throughnoise or focused airflow.

ResMed Limited has developed a number of improved mask venttechnologies. See International Patent Application Publication No. WO1998/034665; International Patent Application Publication No. WO2000/078381; U.S. Pat. No. 6,581,594; US Patent Application PublicationNo. US 2009/0050156; US Patent Application Publication No. 2009/0044808.

Table of noise of prior masks (ISO 17510-2:2007, 10 cmH2O pressure at 1m)

A-weighted A-weighted sound power sound Mask level dB(A) pressure dB(A)Year Mask name type (uncertainty) (uncertainty) (approx.) Glue-on (*)nasal 50.9 42.9 1981 ResCare nasal 31.5 23.5 1993 standard (*) ResMednasal 29.5 21.5 1998 MirageTM (*) ResMed nasal 36 (3) 28 (3) 2000UltraMirageTM ResMed nasal 32 (3) 24 (3) 2002 Mirage ActivaTM ResMednasal 30 (3) 22 (3) 2008 Mirage MicroTM ResMed nasal 29 (3) 22 (3) 2008MirageTM SoftGel ResMed nasal 26 (3) 18 (3) 2010 MirageTM FX ResMednasal 37   29   2004 Mirage pillows SwiftTM (*) ResMed nasal 28 (3) 20(3) 2005 Mirage pillows SwiftTM II ResMed nasal 25 (3) 17 (3) 2008Mirage pillows SwiftTM LT ResMed AirFit nasal 21 (3) 13 (3) 2014 P10pillows (*one specimen only, measured using test method specified in ISO3744 in CPAP mode at 10 cmH2O)

Sound pressure values of a variety of objects are listed below

A-weighted sound Object pressure dB(A) Notes Vacuum cleaner: NilfiskWalter 68 ISO 3744 at 1 m Broadly Litter Hog: B+ Grade distanceConversational speech 60 1 m distance Average home 50 Quiet library 40Quiet bedroom at night 30 Background in TV studio 20

2 BRIEF SUMMARY OF THE TECHNOLOGY

The present technology is directed towards providing medical devicesused in the screening, diagnosis, monitoring, amelioration, treatment,or prevention of respiratory disorders having one or more of improvedcomfort, cost, efficacy, ease of use and manufacturability.

A first aspect of the present technology relates to apparatus used inthe screening, diagnosis, monitoring, amelioration, treatment orprevention of a respiratory disorder.

Another aspect of the present technology relates to methods used in thescreening, diagnosis, monitoring, amelioration, treatment or preventionof a respiratory disorder.

An aspect of certain forms of the present technology is to providemethods and/or apparatus that improve the compliance of patients withrespiratory therapy.

One form of the present technology comprises patient interface with asealing portion configured to seal against a patient's face.

Another aspect of the present technology comprises a mouth cushionconfigured to seal around a patient's mouth and a nasal cushionconfigured to seal around a patient's nares.

Another aspect of the present technology comprises a mouth cushionconfigured to seal around a patient's mouth and a nasal cushionconfigured to seal against an interior of the patient's nostrils.

Another aspect of the present technology comprises a nasal cushionconfigured to seal a patient's nasal airways.

Another aspect of the present technology comprises headgear comprisingan air delivery conduit configured to support a patient interface on apatient's head.

Another aspect of the technology comprises a vent for a patientinterface that includes a surface with at least one vent hole in thesurface.

An aspect of the present technology is directed to a patient interfacethat includes: a mouth plenum chamber pressurisable to a therapeuticpressure of at least 6 cmH₂O above ambient air pressure, said mouthplenum chamber including a plenum chamber inlet port sized andstructured to receive a flow of air at the therapeutic pressure forbreathing by a patient, a seal-forming structure constructed andarranged to form a seal with a region of the patient's face surroundingan entrance to the patient's airways, said seal-forming structure havinga hole therein such that the flow of air at said therapeutic pressure isdelivered to at least an entrance to the patient's nares, theseal-forming structure constructed and arranged to maintain saidtherapeutic pressure in the plenum chamber throughout the patient'srespiratory cycle in use, the seal-forming structure comprising: a mouthportion that forms at least part of the mouth plenum and is configuredto seal around the patient's mouth; a nasal portion that is configuredto seal with the patient's nares, the nasal portion comprising a nasalplenum positioned to receive pressurized gas from the mouth plenum; anda clip configured to connect the mouth plenum to the nasal plenum andact as a conduit for the flow of the pressurized gas from the mouthplenum to the nasal plenum, the clip comprising: a mouth portion endconfigured to engage the mouth portion; a nasal portion end configuredto engage the nasal portion; and a pair of wings protruding from thenasal portion end into an interior of the nasal plenum so that the wingsengage an interior surface of the nasal plenum, a base of each wingbeing positioned on opposing lateral sides of the clip, a positioningand stabilising structure to provide a force to hold the seal-formingstructure in a therapeutically effective position on the patient's head,the positioning and stabilising structure comprising a tie, the tiebeing constructed and arranged so that at least a portion overlies aregion of the patient's head superior to an otobasion superior of thepatient's head in use; and a vent structure to allow a continuous flowof gases exhaled by the patient from an interior of the plenum chamberto ambient, said vent structure being sized and shaped to maintain thetherapeutic pressure in the plenum chamber in use; wherein the patientinterface is configured to allow the patient to breathe from ambientthrough their mouth in the absence of a flow of pressurised air throughthe plenum chamber inlet port.

In examples, (a) the wings may be separate and distinct from each other(b) a height of each wing may be a distance each wing projects from thenasal portion end of the clip, and the maximum height of each wing maybe at the laterally furthest point on the wing, (c) the height of eachwing may vary so that the height of each wing increases toward thelaterally furthest point on the wing, (d) the height of each wing mayvary gradually to form a smooth curve, the height of each wing maydecrease to a value of zero toward a central region of the nasal portionend of the clip, (e) the nasal plenum may comprise an inlet opening, andthe clip may comprise a nasal end flange and a middle flange thattogether may form a nasal end channel configured to receive a rim of theinlet opening of the nasal plenum, the nasal end flange may beconfigured to be inserted into the inlet opening of the nasal plenum,(f) the pair of wings may extend from the nasal end flange, (g) themouth plenum may comprise an outlet opening, and the clip may comprise amouth end flange that together forms a mouth end channel that mayreceive a rim of the outlet opening of the mouth plenum, (h) the mouthend flange may be configured to be inserted into the mouth plenum, (i) arim of the outlet opening of the mouth plenum may comprise a tab andthere may be a notch in the mouth end flange of the clip, and the notchmay be positioned to receive the tab when the nasal portion is connectedto the mouth portion in the correct orientation, (j) the tab may beconfigured to prevent the nasal portion from being secured to the mouthportion in a wrong orientation, (k) an outer surface of the mouthportion may comprise a first printed indicia, an outer surface of thenasal portion may comprise a second printed indicia that lines up withthe first printed indicia when the nasal portion is connected to themouth portion in the correct orientation, and (l) the nasal portion maycomprise a flexible base and a pair of nasal pillows attached to theflexible base, the nasal pillows may be configured to seal with aninterior of the patient's nostrils.

In further example, (a) the mouth portion may comprise a flange havingan inside surface and an outside surface, and the flange may comprise atarget seal-forming region located on an outside surface thereof, (b)the outside surface may comprise a lip region constructed to have a lipsaddle-shaped region, (c) at a point on the outside surface of the mouthportion where the mid-contact plane may touch the target seal-formingregion, the curvature of the lip saddle-shaped region in theinferior-superior direction may have a negative sign and a magnitudethat is larger than a magnitude of the curvature of the lipsaddle-shaped region in the left-right direction, (d) the outsidesurface may comprise a left corner region and a right corner region, (e)the outside surface may be constructed to have a first convexdome-shaped region in said left corner region, (f) the outside surfacemay be constructed to have a second convex dome-shaped region in saidright corner region, (g) the outside surface of said flange may have aninner edge, said hole may be bounded by said inner edge, and said inneredge may include an inner edge lip region, (h) the inner edge of saidflange may be constructed so that a space curve on the outside surfaceof the flange at said inner edge in said left corner region may have aleft-hand positive torsion, (i) the inner edge of said flange may beconstructed so that a space curve on the outside surface of the flangeat said inner edge in said right corner region has a right-hand positivetorsion, (j) the mouth plenum may be partly formed by a shell, which hasa shell inside surface and shell outside surface, and the shell insidesurface may be arranged to be at said therapeutic pressure in use, andsaid shell outside surface may be arranged to be at ambient pressure inuse, (k) the shell may be structured to be rigid when subject to aninternal pressure of less than about 30 cmH2O above ambient pressure,(l) the shell may be constructed from a hard plastic material, (m) theshell may be constructed from a transparent material, (n) the shellinside surface may be constructed to include a concave dome-shapedregion, (o) the positioning and stabilising structure may include asecond tie, the second tie being constructed and arranged so that atleast a portion of a superior edge thereof passes inferior to anotobasion inferior of the patient's head and to overlay or lie inferiorto the occipital bone of the patient's head (p) the positioning andstabilising structure may include a low profile side portion configuredto be positioned under the patient's head while the patient is lying ina side sleeping position, (q) the mouth plenum may be constructed from atransparent material, (r) the patient interface may be configured sothat no part of the patient interface structure enters the mouth in use,or (s) the patient interface may be constructed and arranged so that themouth plenum does not cover the eyes in use.

Another aspect of the present technology is directed to a patientinterface that includes: a mouth plenum chamber pressurisable to atherapeutic pressure of at least 6 cmH₂O above ambient air pressure,said mouth plenum chamber including a plenum chamber inlet port sizedand structured to receive a flow of air at the therapeutic pressure forbreathing by a patient, a seal-forming structure constructed andarranged to form a seal with a region of the patient's face surroundingan entrance to the patient's airways, said seal-forming structure havinga hole therein such that the flow of air at said therapeutic pressure isdelivered to at least an entrance to the patient's nares, theseal-forming structure constructed and arranged to maintain saidtherapeutic pressure in the plenum chamber throughout the patient'srespiratory cycle in use, the seal-forming structure comprising: a nasalportion that is configured to seal with the patient's nares, the nasalportion comprising a nasal plenum positioned to receive pressurized gasfrom the mouth plenum chamber; and a clip configured to connect themouth plenum chamber to the nasal plenum and act as a conduit for theflow of the pressurized gas from the mouth plenum chamber to the nasalplenum, the clip comprising: a mouth portion end configured to engage anoutlet of the mouth plenum chamber; and a nasal portion end configuredto engage the nasal portion, the clip being configured to add rigidityto the lateral sides of the nasal plenum so that the lateral sides ofthe nasal plenum are more rigid than the central portion of the nasalplenum when the clip is attached to the nasal plenum, a positioning andstabilising structure to provide a force to hold the seal-formingstructure in a therapeutically effective position on the patient's head;and a vent structure to allow a continuous flow of gases exhaled by thepatient from an interior of the plenum chamber to ambient, said ventstructure being sized and shaped to maintain the therapeutic pressure inthe plenum chamber in use; wherein the patient interface is configuredto allow the patient to breathe from ambient through their mouth in theabsence of a flow of pressurised air through the plenum chamber inletport.

In examples, (a) the clip may comprise a pair of lateral wings thatextend from an end of the clip, each lateral wing may be located onopposite sides of a lumen in the clip and may be configured to increasethe rigidity of the nasal plenum when the clip is attached to the nasalplenum, (b) a height of each wing may be a distance each wing projectsfrom the end of the clip, and the maximum height of each wing may be atthe laterally furthest point on the wing, (c) the height of each wingmay vary so that the height of each wing increases toward the laterallyfurthest point on the wing, (d) the height of each wing may decrease toa value of zero toward a central region of the nasal portion end of theclip, (e) the nasal portion may comprise a nasal base and a pair ofnasal pillows extending from the nasal base, (f) the nasal base may formthe nasal plenum, (g) the nasal base and the nasal pillows may be formedfrom a flexible material, (h) the clip may be made of a material that ismore rigid than the nasal portion and the mouth portion, (i) the wingsmay be configured to be inserted into the nasal plenum when the clip isattached to the nasal portion, (j) the wings may be configured to lodgeagainst an interior of the nasal plenum when the clip is attached to thenasal plenum, (k) the clip may be removable from the mouth plenum, (l)the clip may be removable from the nasal plenum.

Another aspect of the present technology is directed to a patientinterface that includes: a mouth plenum chamber pressurisable to atherapeutic pressure of at least 6 cmH₂O above ambient air pressure,said mouth plenum chamber including a plenum chamber inlet port sizedand structured to receive a flow of air at the therapeutic pressure forbreathing by a patient, a seal-forming structure constructed andarranged to form a seal with a region of the patient's face surroundingan entrance to the patient's airways, said seal-forming structure havinga hole therein such that the flow of air at said therapeutic pressure isdelivered to at least an entrance to the patient's nares, theseal-forming structure constructed and arranged to maintain saidtherapeutic pressure in the plenum chamber throughout the patient'srespiratory cycle in use, the seal-forming structure comprising: a nasalportion that is configured to seal with the patient's nares, the nasalportion comprising a nasal plenum, the nasal plenum comprising an airinlet configured to receive pressurized gas from the mouth plenumchamber; and a clip configured to connect the mouth plenum chamber tothe nasal plenum and act as a conduit for the flow of the pressurizedgas from the mouth plenum chamber to the nasal plenum, the clipcomprising: a mouth portion end configured to engage an outlet of themouth plenum chamber; a nasal portion end configured to engage the nasalportion; a lumen extending from the mouth portion to the nasal portion;and a pair of wings protruding from the nasal portion end into aninterior of the nasal plenum, the wings being anchored to the nasalportion end at respective bases located on opposite lateral sides of thelumen, each wing extending laterally away from the lumen and terminatingat a free end, a distance between the free ends of the wings beinggreater than a diameter of the air inlet of the nasal plenum; apositioning and stabilising structure to provide a force to hold theseal-forming structure in a therapeutically effective position on thepatient's head; and a vent structure to allow a continuous flow of gasesexhaled by the patient from an interior of the plenum chamber toambient, said vent structure being sized and shaped to maintain thetherapeutic pressure in the plenum chamber in use; wherein the patientinterface is configured to allow the patient to breathe from ambientthrough their mouth in the absence of a flow of pressurised air throughthe plenum chamber inlet port.

In examples, (a) the wings may engage an interior surface of the nasalplenum, (b) the clip may be configured so that a force necessary toinsert the clip into the nasal plenum is less than a force necessary toremove the clip from the nasal plenum, (c) a force necessary to removethe clip from the nasal plenum may be between 19 and 20 N, (d) each wingmay be movable relative to the interior surface of the nasal plenum baseafter the clip is secured to the nasal plenum, (e) the wings may resistthe removal of the clip from the nasal plenum, (f) the clip may comprisea nasal end flange and a middle flange that together form a nasal endchannel configured to receive a rim of the air inlet of the nasalplenum, the nasal end flange may be configured to be inserted into theinlet opening of the nasal plenum, (g) the pair of wings may extend fromthe nasal end flange, the mouth plenum may comprise an outlet opening,and the clip may comprise a mouth end flange that together forms a mouthend channel that receives a rim of the outlet opening of the mouthplenum, (h) the mouth end flange may be configured to be inserted intothe mouth plenum.

Another aspect of the present technology is directed to a patientinterface that includes: a mouth plenum chamber pressurisable to atherapeutic pressure of at least 6 cmH₂O above ambient air pressure,said mouth plenum chamber including a plenum chamber inlet port sizedand structured to receive a flow of air at the therapeutic pressure forbreathing by a patient, a seal-forming structure constructed andarranged to form a seal with a region of the patient's face surroundingan entrance to the patient's airways, said seal-forming structure havinga hole therein such that the flow of air at said therapeutic pressure isdelivered to at least an entrance to the patient's nares, theseal-forming structure constructed and arranged to maintain saidtherapeutic pressure in the plenum chamber throughout the patient'srespiratory cycle in use, the seal-forming structure comprising: a mouthportion that forms at least part of the mouth plenum and is configuredto seal around the patient's mouth, the mouth portion comprising areceptacle with an outlet opening and a pair of mouth portion magnetspositioned on opposite sides of the outlet opening; and a nasal portionthat is configured to seal with the patient's nares, the nasal portioncomprising a nasal plenum with an inlet opening and a pair of nasalportion magnets positioned on opposite sides of the inlet opening, thenasal plenum being configured to be received within the receptacle andthe nasal portion magnets being positioned so that both of the nasalportion magnets are between the mouth portion magnets when the nasalplenum is received within the receptacle; a positioning and stabilisingstructure to provide a force to hold the seal-forming structure in atherapeutically effective position on the patient's head; and a ventstructure to allow a continuous flow of gases exhaled by the patientfrom an interior of the plenum chamber to ambient, said vent structurebeing sized and shaped to maintain the therapeutic pressure in theplenum chamber in use; wherein the patient interface is configured toallow the patient to breathe from ambient through their mouth in theabsence of a flow of pressurised air through the plenum chamber inletport.

In examples, (a) the receptacle may comprise at least one side wallextending from the base, and the mouth portion magnets may be positionedon the at least one side wall, (b) the nasal plenum may comprise atleast one side wall and the nasal portion magnets may be positioned onthe at least one side wall, (c) the nasal portion magnets may be onlateral sides of the nasal plenum, (d) the mouth portion magnets may beon lateral sides of the receptacle, (e) the nasal portion magnets may beoriented to present different polarities toward the mouth portionmagnets, (f) the mouth portion magnets may be oriented to presentdifferent polarities toward the nasal portion magnets, (g) the nasalportion magnets and the mouth portion magnets may be oriented to repeleach other when the nasal plenum is inserted into the receptacle in thewrong orientation, (h) the nasal portion magnets and the mouth portionmagnets may be configured to connect two flexible bodies, (i) the nasalportion magnets may be molded to the nasal plenum and the mouth portionmagnets may be molded to the receptacle, (j) a bottom of a rim of theinlet opening in the nasal plenum may comprise a lip seal, (k) the lipseal may be configured to engage a rim of the outlet opening of thereceptacle when the nasal plenum may be secured within the receptacle,(l) the lip seal may be positioned below the nasal portion magnets, (m)the nasal portion magnets may face each other (n) the mouth portionmagnets may face each other.

Another aspect of the present technology is directed to a patientinterface that includes: a mouth plenum chamber pressurisable to atherapeutic pressure of at least 6 cmH₂O above ambient air pressure,said mouth plenum chamber including a plenum chamber inlet port sizedand structured to receive a flow of air at the therapeutic pressure forbreathing by a patient, a seal-forming structure constructed andarranged to form a seal with a region of the patient's face surroundingan entrance to the patient's airways, said seal-forming structure havinga hole therein such that the flow of air at said therapeutic pressure isdelivered to at least an entrance to the patient's nares, theseal-forming structure constructed and arranged to maintain saidtherapeutic pressure in the plenum chamber throughout the patient'srespiratory cycle in use, the seal-forming structure comprising: a mouthportion that forms at least part of the mouth plenum and is configuredto seal around the patient's mouth; and a nasal portion that isconfigured to seal with the patient's nares, the nasal portioncomprising a nasal plenum with an inlet opening, the nasal plenum beingconfigured to be received within the receptacle; a positioning andstabilising structure to provide a force to hold the seal-formingstructure in a therapeutically effective position on the patient's head;and a vent structure to allow a continuous flow of gases exhaled by thepatient from an interior of the plenum chamber to ambient, said ventstructure being sized and shaped to maintain the therapeutic pressure inthe plenum chamber in use, the vent structure comprising: a main bodyconfigured to be secured to the mouth portion, the main body comprisinga vent wall with a plurality of vent holes, a receptacle, and a pair ofanchor sockets located on opposing lateral sides of the receptacle; acover comprising a pair of anchor pegs on lateral sides of the cover,the anchor pegs being configured to be inserted into the anchor socketsto secure the cover to the main body; and a diffuser received within thereceptacle between the anchor sockets, the diffuser being sandwichedbetween the main body and the cover, wherein the patient interface isconfigured to allow the patient to breathe from ambient through theirmouth in the absence of a flow of pressurised air through the plenumchamber inlet port.

In examples, (a) the anchor sockets may be keyed with the anchor pegs sothat only anchor pegs with the same shape as the anchor sockets arereceivable within the anchor sockets, (b) the anchor sockets may betapered so that the anchor pegs become wedged in the anchor sockets whenthe cover is secured to the main body, (c) the main body may comprise afirst flange and a second flange that forms a channel with the firstflange, the mouth portion may comprise a vent opening and a rim of thevent opening may be received in the channel when the main body issecured to the mouth portion, (d) the anchor sockets may extend deeperthan the channel, (e) the vent wall may enclose an end of the receptaclethat is closest to the interior of the mouth plenum, (f) the diffusermay be spaced apart from the vent holes, (g) each anchor socket may havea different size, (h) each anchor socket may have a different shape, (i)the anchor sockets may be configured to prevent the cover from beingsecured to the main body in the wrong orientation, (j) a perimeter ofthe cover may be smaller than a perimeter of the main body so that a gapmay be formed between the main body and the cover when the cover issecured to the main body, (k) the vent holes may be tapered so that thevent holes narrow in a direction toward the diffuser, (l) opposing sidesof the interior wall of each vent hole may form an angle of taper 10 to35 degrees, (m) the angle of taper may be about 10 degrees, (n) theangle of taper may be about 35 degrees, (o) a base of each vent hole maybe flared, (p) the flared portion of the vent hole may have a radius ofcurvature of 0.2 mm to 0.4 mm, (q) the radius of curvature may be about0.25 mm, (r) the radius of curvature may be about 0.3 mm, (s) a smallestdiameter of each vent hole may be 0.5 mm to 2.0 mm, (t) the smallestdiameter may be 0.89 mm, (u) the smallest diameter may be 0.98 mm, (v)the smallest diameter may be 1.01 mm, (w) the smallest diameter may be1.17 mm.

Another aspect of the present technology is directed to a patientinterface that includes: a mouth plenum chamber pressurisable to atherapeutic pressure of at least 6 cmH₂O above ambient air pressure,said mouth plenum chamber including a plenum chamber inlet port sizedand structured to receive a flow of air at the therapeutic pressure forbreathing by a patient, a seal-forming structure constructed andarranged to form a seal with a region of the patient's face surroundingan entrance to the patient's airways, said seal-forming structure havinga hole therein such that the flow of air at said therapeutic pressure isdelivered to at least an entrance to the patient's nares, theseal-forming structure constructed and arranged to maintain saidtherapeutic pressure in the plenum chamber throughout the patient'srespiratory cycle in use, the seal-forming structure comprising: a mouthportion that forms at least part of the mouth plenum and is configuredto seal around the patient's mouth; and a nasal portion that isconfigured to seal with the patient's nares, the nasal portioncomprising a nasal plenum with an inlet opening, the nasal plenum beingconfigured to be received within the receptacle; a positioning andstabilising structure to provide a force to hold the seal-formingstructure in a therapeutically effective position on the patient's head;and a vent structure to allow a continuous flow of gases exhaled by thepatient from an interior of the plenum chamber to ambient, said ventstructure being sized and shaped to maintain the therapeutic pressure inthe plenum chamber in use, the vent structure comprising: a vent wallwith a plurality of vent openings and a trough on an outwardly facingsurface that completely encircles the vent openings; at least one sidewall extending from the vent wall; and a flange extending from an end ofthe at least one side wall so that an edge of the vent wall, an outersurface of the at least one side wall, and the flange together form achannel configured to receive a rim around the vent opening in the mouthportion, the flange being configured to be received inside the mouthplenum, wherein the patient interface is configured to allow the patientto breathe from ambient through their mouth in the absence of a flow ofpressurised air through the plenum chamber inlet port.

In examples, (a) the outwardly facing surface of the vent wall may beconvex and an inwardly facing surface of the vent wall opposite theoutwardly facing surface may be convex, (b) the vent holes may betapered so that the vent holes narrow in a direction toward theoutwardly facing surface of the vent wall, (c) opposing sides of theinterior wall of each vent hole may form an angle of taper 10 to 35degrees, (d) the angle of taper may be about 10 degrees, (e) the angleof taper may be about 35 degrees, (f) a base of each vent hole may beflared, (g) the flared portion of the vent hole may have a radius ofcurvature of 0.2 mm to 0.4 mm, (h) the radius of curvature may be about0.25 mm, (i) the radius of curvature may be about 0.3 mm, (j) a smallestdiameter of each vent hole may be 0.5 mm to 2.0 mm, (k) the smallestdiameter may be 0.89 mm, (l) the smallest diameter may be 0.98 mm, (m)the smallest diameter may be 1.01 mm, (n) the smallest diameter may be1.17 mm.

In yet another aspect of the present technology is directed to arespiratory therapy system that includes: the patient interfaceaccording to any of the aspects of the present technology discussedabove; a respiratory pressure therapy device configured to generate theflow of air at the therapeutic pressure; and an air circuit configuredto direct the flow of air at the therapeutic pressure from therespiratory pressure therapy device to the patient interface.

Another aspect of one form of the present technology is a patientinterface that is moulded or otherwise constructed with a perimetershape which is complementary to that of an intended wearer.

An aspect of one form of the present technology is a method ofmanufacturing apparatus.

An aspect of certain forms of the present technology is a medical devicethat is easy to use, e.g. by a person who does not have medicaltraining, by a person who has limited dexterity, vision or by a personwith limited experience in using this type of medical device.

An aspect of one form of the present technology is a portable RPT devicethat may be carried by a person, e.g., around the home of the person.

An aspect of one form of the present technology is a patient interfacethat may be washed in a home of a patient, e.g., in soapy water, withoutrequiring specialised cleaning equipment. An aspect of one form of thepresent technology is a humidifier tank that may be washed in a home ofa patient, e.g., in soapy water, without requiring specialised cleaningequipment.

The methods, systems, devices and apparatus described may be implementedso as to improve the functionality of a processor, such as a processorof a specific purpose computer, respiratory monitor and/or a respiratorytherapy apparatus. Moreover, the described methods, systems, devices andapparatus can provide improvements in the technological field ofautomated management, monitoring and/or treatment of respiratoryconditions, including, for example, sleep disordered breathing.

Of course, portions of the aspects may form sub-aspects of the presenttechnology. Also, various ones of the sub-aspects and/or aspects may becombined in various manners and also constitute additional aspects orsub-aspects of the present technology.

Other features of the technology will be apparent from consideration ofthe information contained in the following detailed description,abstract, drawings and claims.

3 BRIEF DESCRIPTION OF THE DRAWINGS

The present technology is illustrated by way of example, and not by wayof limitation, in the figures of the accompanying drawings, in whichlike reference numerals refer to similar elements including:

3.1 Respiratory Therapy Systems

FIG. 1A shows a system including a patient 1000 wearing a patientinterface 3000, in the form of nasal pillows, receiving a supply of airat positive pressure from an RPT device 4000. Air from the RPT device4000 is humidified in a humidifier 5000, and passes along an air circuit4170 to the patient 1000. A bed partner 1100 is also shown. The patientis sleeping in a supine sleeping position.

FIG. 1B shows a system including a patient 1000 wearing a patientinterface 3000, in the form of a nasal mask, receiving a supply of airat positive pressure from an RPT device 4000. Air from the RPT device ishumidified in a humidifier 5000, and passes along an air circuit 4170 tothe patient 1000.

FIG. 1C shows a system including a patient 1000 wearing a patientinterface 3000, in the form of a full-face mask, receiving a supply ofair at positive pressure from an RPT device 4000. Air from the RPTdevice is humidified in a humidifier 5000, and passes along an aircircuit 4170 to the patient 1000. The patient is sleeping in a sidesleeping position.

3.2 Respiratory System and Facial Anatomy

FIG. 2A shows an overview of a human respiratory system including thenasal and oral cavities, the larynx, vocal folds, oesophagus, trachea,bronchus, lung, alveolar sacs, heart and diaphragm.

FIG. 2B shows a view of a human upper airway including the nasal cavity,nasal bone, lateral nasal cartilage, greater alar cartilage, nostril,lip superior, lip inferior, larynx, hard palate, soft palate,oropharynx, tongue, epiglottis, vocal folds, oesophagus and trachea.

FIG. 2C is a front view of a face with several features of surfaceanatomy identified including the lip superior, upper vermilion, lowervermilion, lip inferior, mouth width, endocanthion, a nasal ala,nasolabial sulcus and cheilion. Also indicated are the directionssuperior, inferior, radially inward and radially outward.

FIG. 2D is a side view of a head with several features of surfaceanatomy identified including glabella, sellion, pronasale, subnasale,lip superior, lip inferior, supramenton, nasal ridge, alar crest point,otobasion superior and otobasion inferior. Also indicated are thedirections superior & inferior, and anterior & posterior.

FIG. 2E is a further side view of a head. The approximate locations ofthe Frankfort horizontal and nasolabial angle are indicated. The coronalplane is also indicated.

FIG. 2F shows a base view of a nose with several features identifiedincluding naso-labial sulcus, lip inferior, upper Vermilion, naris,subnasale, columella, pronasale, the major axis of a naris and themidsagittal plane.

FIG. 2G shows a side view of the superficial features of a nose.

FIG. 2H shows subcutaneal structures of the nose, including lateralcartilage, septum cartilage, greater alar cartilage, lesser alarcartilage, sesamoid cartilage, nasal bone, epidermis, adipose tissue,frontal process of the maxilla and fibrofatty tissue.

FIG. 2I shows a medial dissection of a nose, approximately severalmillimeters from the midsagittal plane, amongst other things showing theseptum cartilage and medial crus of greater alar cartilage.

FIG. 2J shows a front view of the bones of a skull including thefrontal, nasal and zygomatic bones. Nasal concha are indicated, as arethe maxilla, and mandible.

FIG. 2K shows a lateral view of a skull with the outline of the surfaceof a head, as well as several muscles. The following bones are shown:frontal, sphenoid, nasal, zygomatic, maxilla, mandible, parietal,temporal and occipital. The mental protuberance is indicated. Thefollowing muscles are shown: digastricus, masseter, sternocleidomastoidand trapezius.

FIG. 2L shows an anterolateral view of a nose.

3.3 Patient Interface

FIG. 3A shows a patient interface in the form of a nasal mask inaccordance with one form of the present technology.

FIG. 3B shows a schematic of a cross-section through a structure at apoint. An outward normal at the point is indicated. The curvature at thepoint has a positive sign, and a relatively large magnitude whencompared to the magnitude of the curvature shown in FIG. 3C.

FIG. 3C shows a schematic of a cross-section through a structure at apoint. An outward normal at the point is indicated. The curvature at thepoint has a positive sign, and a relatively small magnitude whencompared to the magnitude of the curvature shown in FIG. 3B.

FIG. 3D shows a schematic of a cross-section through a structure at apoint. An outward normal at the point is indicated. The curvature at thepoint has a value of zero.

FIG. 3E shows a schematic of a cross-section through a structure at apoint. An outward normal at the point is indicated. The curvature at thepoint has a negative sign, and a relatively small magnitude whencompared to the magnitude of the curvature shown in FIG. 3F.

FIG. 3F shows a schematic of a cross-section through a structure at apoint. An outward normal at the point is indicated. The curvature at thepoint has a negative sign, and a relatively large magnitude whencompared to the magnitude of the curvature shown in FIG. 3E.

FIG. 3G shows a cushion for a mask that includes two pillows. Anexterior surface of the cushion is indicated. An edge of the surface isindicated. Dome and saddle regions are indicated.

FIG. 3H shows a cushion for a mask. An exterior surface of the cushionis indicated. An edge of the surface is indicated. A path on the surfacebetween points A and B is indicated. A straight line distance between Aand B is indicated. Two saddle regions and a dome region are indicated.

FIG. 3I shows the surface of a structure, with a one dimensional hole inthe surface. The illustrated plane curve forms the boundary of a onedimensional hole.

FIG. 3J shows a cross-section through the structure of FIG. 3I. Theillustrated surface bounds a two dimensional hole in the structure ofFIG. 3I.

FIG. 3K shows a perspective view of the structure of FIG. 3I, includingthe two dimensional hole and the one dimensional hole. Also shown is thesurface that bounds a two dimensional hole in the structure of FIG. 3I.

FIG. 3L shows a mask having an inflatable bladder as a cushion.

FIG. 3M shows a cross-section through the mask of FIG. 3L, and shows theinterior surface of the bladder. The interior surface bounds the twodimensional hole in the mask.

FIG. 3N shows a further cross-section through the mask of FIG. 3L. Theinterior surface is also indicated.

FIG. 3O illustrates a left-hand rule.

FIG. 3P illustrates a right-hand rule.

FIG. 3Q shows a left ear, including the left ear helix.

FIG. 3R shows a right ear, including the right ear helix.

FIG. 3S shows a right-hand helix.

FIG. 3T shows a view of a mask, including the sign of the torsion of thespace curve defined by the edge of the sealing membrane in differentregions of the mask.

FIG. 3U shows a view of a plenum chamber 3200 showing a sagittal planeand a mid-contact plane.

FIG. 3V shows a view of a posterior of the plenum chamber of FIG. 3U.The direction of the view is normal to the mid-contact plane. Thesagittal plane in FIG. 3V bisects the plenum chamber into left-hand andright-hand sides.

FIG. 3W shows a cross-section through the plenum chamber of FIG. 3V, thecross-section being taken at the sagittal plane shown in FIG. 3V. A‘mid-contact’ plane is shown. The mid-contact plane is perpendicular tothe sagittal plane. The orientation of the mid-contact plane correspondsto the orientation of a chord 3210 which lies on the sagittal plane andjust touches the cushion of the plenum chamber at two points on thesagittal plane: a superior point 3220 and an inferior point 3230.Depending on the geometry of the cushion in this region, the mid-contactplane may be a tangent at both the superior and inferior points.

FIG. 3X shows the plenum chamber 3200 of FIG. 3U in position for use ona face. The sagittal plane of the plenum chamber 3200 generallycoincides with the midsagittal plane of the face when the plenum chamberis in position for use. The mid-contact plane corresponds generally tothe ‘plane of the face’ when the plenum chamber is in position for use.In FIG. 3X the plenum chamber 3200 is that of a nasal mask, and thesuperior point 3220 sits approximately on the sellion, while theinferior point 3230 sits on the lip superior.

FIG. 3Y shows a patient interface in the form of a nasal cannula inaccordance with one form of the present technology.

3.4 RPT Device

FIG. 4A shows an RPT device in accordance with one form of the presenttechnology.

FIG. 4B is a schematic diagram of the pneumatic path of an RPT device inaccordance with one form of the present technology. The directions ofupstream and downstream are indicated with reference to the blower andthe patient interface. The blower is defined to be upstream of thepatient interface and the patient interface is defined to be downstreamof the blower, regardless of the actual flow direction at any particularmoment. Items which are located within the pneumatic path between theblower and the patient interface are downstream of the blower andupstream of the patient interface.

3.5 Humidifier

FIG. 5A shows an isometric view of a humidifier in accordance with oneform of the present technology.

FIG. 5B shows an isometric view of a humidifier in accordance with oneform of the present technology, showing a humidifier reservoir 5110removed from the humidifier reservoir dock 5130.

3.6 Examples of the Present Technology

FIG. 6 shows an exemplary patient interface in accordance with one formof the present technology.

FIG. 7 shows an exploded view of the patient interface of FIG. 7 .

FIG. 8 shows a rear view of a main body of the patient interface of FIG.7 .

FIG. 9 shows a cross-sectional view of a nasal pillow module inaccordance with an aspect of the technology.

FIGS. 9A-9C show cross-sectional views of flanges of the nasal pillowmodule.

FIGS. 10-12 show different views of an exemplary cushion clip.

FIG. 13 shows a cross-sectional view of a nasal pillow module inaccordance with another aspect of the technology.

FIGS. 14-16 show different views of another exemplary cushion clip.

FIG. 17 shows a cross-sectional view of the main body of the patientinterface.

FIG. 18 shows another view of the cushion clip.

FIG. 19 shows an exploded view of another exemplary patient interface.

FIG. 20 shows a nasal pillow module according to another aspect of thetechnology.

FIG. 21 shows another view of the nasal pillow module of FIG. 20 .

FIG. 22 shows a cross-sectional view of the patient interface of FIG. 19.

FIG. 23 shows an enlarged view of the connection between the nasalmodule and the mouth cushion.

FIG. 24 shows an exemplary magnet according to an aspect of the presenttechnology.

FIG. 25 shows an exploded view of an exemplary vent assembly.

FIG. 26 shows the vent assembly of FIG. 25 in assembled form.

FIG. 27 shows a main body of the vent assembly of FIG. 25 .

FIG. 28 shows a cross-sectional view of the main body of FIG. 27 .

FIGS. 29 and 30 show detailed views of an anchor receptacle of the ventassembly.

FIG. 31 shows another exploded view of the vent assembly of FIG. 25 .

FIG. 32 shows a main body of a vent assembly according to another aspectof the technology.

FIG. 33 shows a cross-sectional view of the main body of FIG. 32 .

FIGS. 34 and 35 show detailed view of an anchor receptacle of the ventassembly.

FIG. 36 shows a rear view of a vent according to another aspect of thepresent technology.

FIG. 37 shows another view of the vent of FIG. 36 .

FIG. 38 shows a cross-sectional view of the vent of FIG. 36 .

FIG. 39 shows a vent according to another aspect of the presenttechnology.

FIG. 40 shows a cross-sectional view of the vent of FIG. 39 .

4 DETAILED DESCRIPTION OF EXAMPLES OF THE TECHNOLOGY

Before the present technology is described in further detail, it is tobe understood that the technology is not limited to the particularexamples described herein, which may vary. It is also to be understoodthat the terminology used in this disclosure is for the purpose ofdescribing only the particular examples discussed herein, and is notintended to be limiting.

The following description is provided in relation to various exampleswhich may share one or more common characteristics and/or features. Itis to be understood that one or more features of any one example may becombinable with one or more features of another example or otherexamples. In addition, any single feature or combination of features inany of the examples may constitute a further example.

4.1 Therapy

In one form, the present technology comprises a method for treating arespiratory disorder comprising applying positive pressure to theentrance of the airways of a patient 1000.

In certain examples of the present technology, a supply of air atpositive pressure is provided to the nasal passages of the patient viaone or both nares.

In certain examples of the present technology, mouth breathing islimited, restricted or prevented.

4.2 Respiratory Therapy Systems

In one form, the present technology comprises a respiratory therapysystem for treating a respiratory disorder. The respiratory therapysystem may comprise an RPT device 4000 for supplying a flow of air tothe patient 1000 via an air circuit 4170 and a patient interface 3000 or3800.

4.3 Patient Interface

A non-invasive patient interface 3000 in accordance with one aspect ofthe present technology comprises the following functional aspects: aseal-forming structure 3100, a plenum chamber 3200, a positioning andstabilising structure 3300, a vent 3400, one form of connection port3600 for connection to air circuit 4170, and (optionally) a foreheadsupport 3700. In some forms a functional aspect may be provided by oneor more physical components. In some forms, one physical component mayprovide one or more functional aspects. In use the seal-formingstructure 3100 is arranged to surround an entrance to the airways of thepatient so as to maintain positive pressure at the entrance(s) to theairways of the patient 1000. The sealed patient interface 3000 istherefore suitable for delivery of positive pressure therapy.

An unsealed patient interface 3800, in the form of a nasal cannula,includes nasal prongs 3810 a, 3810 b which can deliver air to respectivenares of the patient 1000 via respective orifices in their tips. Suchnasal prongs do not generally form a seal with the inner or outer skinsurface of the nares. This type of interface results in one or more gapsthat are present in use by design (intentional) but they are typicallynot fixed in size such that they may vary unpredictably by movementduring use. This can present a complex pneumatic variable for arespiratory therapy system when pneumatic control and/or assessment isimplemented, unlike other types of mask-based respiratory therapysystems. The air to the nasal prongs may be delivered by one or more airsupply lumens 3820 a, 3820 b that are coupled with the nasalcannula-type unsealed patient interface 3800. The lumens 3820 a, 3820 blead from the nasal cannula-type unsealed patient interface 3800 to arespiratory therapy device via an air circuit. The unsealed patientinterface 3800 is particularly suitable for delivery of flow therapies,in which the RPT device generates the flow of air at controlled flowrates rather than controlled pressures. The “vent” or gap at theunsealed patient interface 3800, through which excess airflow escapes toambient, is the passage between the end of the prongs 3810 a and 3810 bof the nasal cannula-type unsealed patient interface 3800 via thepatient's nares to atmosphere.

If a patient interface is unable to comfortably deliver a minimum levelof positive pressure to the airways, the patient interface may beunsuitable for respiratory pressure therapy.

The patient interface 3000 in accordance with one form of the presenttechnology is constructed and arranged to be able to provide a supply ofair at a positive pressure of at least 6 cmH2O with respect to ambient.

The patient interface 3000 in accordance with one form of the presenttechnology is constructed and arranged to be able to provide a supply ofair at a positive pressure of at least 10 cmH2O with respect to ambient.

The patient interface 3000 in accordance with one form of the presenttechnology is constructed and arranged to be able to provide a supply ofair at a positive pressure of at least 20 cmH₂₀ with respect to ambient.

4.3.1 Seal-Forming Structure

In one form of the present technology, a seal-forming structure 3100provides a target seal-forming region, and may additionally provide acushioning function. The target seal-forming region is a region on theseal-forming structure 3100 where sealing may occur. The region wheresealing actually occurs—the actual sealing surface—may change within agiven treatment session, from day to day, and from patient to patient,depending on a range of factors including for example, where the patientinterface was placed on the face, tension in the positioning andstabilising structure and the shape of a patient's face.

In one form the target seal-forming region is located on an outsidesurface of the seal-forming structure 3100.

In certain forms of the present technology, the seal-forming structure3100 is constructed from a biocompatible material, e.g. silicone rubber.

A seal-forming structure 3100 in accordance with the present technologymay be constructed from a soft, flexible, resilient material such assilicone.

In certain forms of the present technology, a system is providedcomprising more than one a seal-forming structure 3100, each beingconfigured to correspond to a different size and/or shape range. Forexample the system may comprise one form of a seal-forming structure3100 suitable for a large sized head, but not a small sized head andanother suitable for a small sized head, but not a large sized head.

4.3.1.1 Sealing Mechanisms

In one form, the seal-forming structure includes a sealing flangeutilizing a pressure assisted sealing mechanism. In use, the sealingflange can readily respond to a system positive pressure in the interiorof the plenum chamber 3200 acting on its underside to urge it into tightsealing engagement with the face. The pressure assisted mechanism mayact in conjunction with elastic tension in the positioning andstabilising structure.

In one form, the seal-forming structure 3100 comprises a sealing flangeand a support flange. The sealing flange comprises a relatively thinmember with a thickness of less than about 1 mm, for example about 0.25mm to about 0.45 mm, which extends around the perimeter of the plenumchamber 3200. Support flange may be relatively thicker than the sealingflange. The support flange is disposed between the sealing flange andthe marginal edge of the plenum chamber 3200, and extends at least partof the way around the perimeter. The support flange is or includes aspring-like element and functions to support the sealing flange frombuckling in use.

In one form, the seal-forming structure may comprise a compressionsealing portion or a gasket sealing portion. In use the compressionsealing portion, or the gasket sealing portion is constructed andarranged to be in compression, e.g. as a result of elastic tension inthe positioning and stabilising structure.

In one form, the seal-forming structure comprises a tension portion. Inuse, the tension portion is held in tension, e.g. by adjacent regions ofthe sealing flange.

In one form, the seal-forming structure comprises a region having atacky or adhesive surface.

In certain forms of the present technology, a seal-forming structure maycomprise one or more of a pressure-assisted sealing flange, acompression sealing portion, a gasket sealing portion, a tensionportion, and a portion having a tacky or adhesive surface.

4.3.1.2 Upper Lip Region

In one form, the non-invasive patient interface 3000 comprises aseal-forming structure that forms a seal in use on an upper lip region(that is, the lip superior) of the patient's face.

In one form, the seal-forming structure includes a saddle-shaped regionconstructed to form a seal in use on an upper lip region of thepatient's face.

4.3.1.3 Chin-Region

In one form the non-invasive patient interface 3000 comprises aseal-forming structure that forms a seal in use on a chin-region of thepatient's face.

In one form, the seal-forming structure includes a saddle-shaped regionconstructed to form a seal in use on a chin-region of the patient'sface.

4.3.1.4 Nasal Pillows

In one form the seal-forming structure of the non-invasive patientinterface 3000 comprises a pair of nasal puffs, or nasal pillows, eachnasal puff or nasal pillow being constructed and arranged to form a sealwith a respective naris of the nose of a patient.

Nasal pillows in accordance with an aspect of the present technologyinclude: a frusto-cone, at least a portion of which forms a seal on anunderside of the patient's nose, a stalk, a flexible region on theunderside of the frusto-cone and connecting the frusto-cone to thestalk. In addition, the structure to which the nasal pillow of thepresent technology is connected includes a flexible region adjacent thebase of the stalk. The flexible regions can act in concert to facilitatea universal joint structure that is accommodating of relative movementboth displacement and angular of the frusto-cone and the structure towhich the nasal pillow is connected. For example, the frusto-cone may beaxially displaced towards the structure to which the stalk is connected.

4.3.2 Plenum Chamber

The plenum chamber 3200 has a perimeter that is shaped to becomplementary to the surface contour of the face of an average person inthe region where a seal will form in use. In use, a marginal edge of theplenum chamber 3200 is positioned in close proximity to an adjacentsurface of the face. Actual contact with the face is provided by theseal-forming structure 3100. The seal-forming structure 3100 may extendin use about the entire perimeter of the plenum chamber 3200. In someforms, the plenum chamber 3200 and the seal-forming structure 3100 areformed from a single homogeneous piece of material.

In certain forms of the present technology, the plenum chamber 3200 doesnot cover the eyes of the patient in use. In other words, the eyes areoutside the pressurised volume defined by the plenum chamber. Such formstend to be less obtrusive and/or more comfortable for the wearer, whichcan improve compliance with therapy.

In certain forms of the present technology, a wall 3211 bounding atleast part of the plenum chamber 3200 is constructed from a transparentmaterial, e.g. a transparent polycarbonate. The use of a transparentmaterial can reduce the obtrusiveness of the patient interface, and helpimprove compliance with therapy. The use of a transparent material canaid a clinician to observe how the patient interface is located andfunctioning.

In certain forms of the present technology, the wall 3211 bounding atleast part of the plenum chamber 3200 is constructed from a translucentmaterial. The use of a translucent material can reduce the obtrusivenessof the patient interface, and help improve compliance with therapy.

4.3.3 Main Body

FIG. 6 shows an exemplary patient interface 3000 according to one aspectof the technology. As can be seen, the patient interface comprises amain body 3010 and a positioning and stabilising structure 3300 thatsupports the main body 3010. It should be understood that the patientinterface 3000 may also be referred to as a patient interface assembly.When the patient interface 3000 is referred to as a patient interfaceassembly, the main body 3010 may be referred to as a patient interface.

Looking at FIG. 7 , the main body 3010 may comprise the seal-formingstructure 3100 and the wall 3211 bounding the plenum chamber 3200. It iscontemplated that the main body 3010 may also be referred to as a corebody of the patient interface 3000. The main body 3010 may also bereferred to as a cushion and shell assembly, cushion and frame assembly,or cushion/frame with the seal-forming structure 3100 forming thecushion portion and the wall 3211 forming the shell or frame portion. Itis contemplated that the wall 3211 may also be referred to as a frame ora shell.

The wall 3211 may form at least part of an anterior side of the plenum3200. In addition, the positioning and stabilising structure 3300 may beconnected to the main body 3010 at the wall 3211. In particular, thewall 3211 may include a pair of upper headgear connectors 3221 and apair of lower headgear connectors 3231 that are positioned at a locationthat is inferior to the upper headgear connectors 3221.

The upper headgear connectors 3221 may be located on opposing lateralsides of the center of the main body 3010. In addition, the upperheadgear connectors 3221 may be configured to connect to correspondingupper headgear straps and/or conduits of the positioning and stabilizingstructure 3300. The upper headgear connectors 3221 may be in the form ofopenings in the wall 3211 and may function as gas or air inlets to theplenum 3200. In other words, pressurized respiratory gas from the RPTdevice 4000 may enter the main body 3010 by way of the upper headgearconnectors 3221. In addition, the upper headgear connectors 3221 mayform part of a magnetic connection and/or mechanical connection with thecorresponding upper headgear strap and/or conduit.

The lower headgear connectors 3231 may be located on opposing lateralsides of the center of the main body 3010. In addition, the lowerheadgear connectors may be configured to corresponding lower headgearstraps and/or conduits of the positioning and stabilizing structure3300. The lower headgear connectors 3231 may have a different structureand may connect differently to the positioning and stabilizing structure3300 than the upper headgear connectors 3221. The lower headgearconnectors 3231 may form part of a magnetic connection and/or amechanical connection with the corresponding lower headgear strap and/orconduit. In addition, it is contemplated that the lower headgearconnectors 3231 may be rotatable and/or resiliently flexible. Inaddition, although the lower headgear connectors 3231 are illustrated asbeing components on the wall 3211 (see FIGS. 6 and 7 ), it iscontemplated that the lower headgear connectors 3231 may be openings inthe wall 3211.

In some configurations, either the upper headgear connectors 3221 or thelower headgear connectors 3231 may be omitted. In configurations withonly the lower headgear connectors 3231, the lower headgear connectors3231 may be openings in the wall 3211 that function as air/gas inletsinto the plenum 3200. It is also contemplated that the structures of theupper headgear connectors 3221 and the lower headgear connectors 3231may be swapped. That is the lower headgear connectors 3231 may beopenings in the wall 3211, and the upper headgear connectors 3221 may belocated on the wall 3211.

It is contemplated that the wall 3211 may have any number of shapes. Oneexemplary shape is illustrated in FIGS. 6 and 7 . The exemplary shape ofthe wall 3211 of FIGS. 6 and 7 has inferior and superior sides that arefurther apart at the lateral sides than at the central portion. It isfurther contemplated that the wall 3211 may be curved so that aninterior side of the wall 3211 (i.e., the side facing the plenum 3200)is concave while an exterior side of the wall 3211 (i.e., the sidefacing away from the plenum 3200) is convex. Accordingly, the entireexterior surface of the wall 3211 may be dome-shaped.

The seal-forming structure 3100 may be in the form of a flexibleoro-nasal cushion that may comprise a mouth (or oral) portion 3105configured to seal around the patient's mouth and may comprise a nasalportion 3110 configured to seal the patient's nares.

The mouth portion 3105 may cooperate with the wall 3211 to form theplenum 3200. In addition, the mouth portion 3105 may comprise a firstopening 3115 that receives the wall 3211. The inferior and superiorsides of the first opening 3115 may be further apart at the lateralsides than at the central portion. The wall 3211 may be secured to themouth portion 3105 by a sonic weld, an adhesive, a mechanical bond, ormechanical fasteners. It is further contemplated that the wall 3211 maybe molded to the mouth portion 3105.

The mouth portion 3105 may include a continuous target seal-formingregion around the patient's mouth that is configured to engage thepatient's upper lip and the patient's chin. The mouth portion 3105 mayinclude a sealing flap on a posterior side that forms a rim around asecond opening 3120 (see FIG. 8 ). The second opening 3120 may bepositioned so that pressurized respiratory gas flowing through thesecond opening 3120 is directly discharged into the patient's mouth inuse.

In addition, it is contemplated that the sealing flap may be saddleshaped in the regions intersected by a plane that bisects the main body3010 into right and left sides (or the patient's sagittal plane) may besaddle shaped. That is both the central superior and central inferiorsides of the sealing flap may be saddle shaped. In addition, each of thesaddle shaped portions of the sealing flap may be positioned betweendome shaped regions. Also, lateral sides of the sealing flap may have acylindrical shape and may be positioned between opposing dome shapedregions.

It is contemplated that the mouth portion 3105 may include a thirdopening 3125 configured to receive a vent assembly 3400. The thirdopening 3125 may be located on an anterior facing side of the mouthportion 3105. The vent assembly 3400 will be described in more detail,later. It is contemplated that the surface of the mouth portion 3105around the third opening may be dome shaped.

A superior (or upper) surface of the mouth portion 3105 may form areceptacle 3130 configured to receive the nasal portion 3110. Thereceptacle 3130 may be in the form of a recess in the mouth portion 3105and may be referred to as any type of recess such as, for example, apocket, an indentation, a bowl, a socket, a basin, a trough.

The receptacle 3130 may comprise a base 3135 at a base of the receptacle3130 and at least one side wall 3140 extending from the base 3135, theat least one side wall 3140 terminating at an outer rim 3145 of thereceptacle 3130. The base 3135 and the at least one side wall 3140 mayform a receiving space 3150 that receives the nasal portion 3110. Thereceiving space 3150 may be shaped so that a perimeter of the receptacle3130 at the outer rim 3145 is larger than the perimeter of thereceptacle 3130 at the base 3135. In addition, the receiving space 3150may be separated from the plenum 3200 by the base 3135 and the at leastone side wall 3140. Also, a fourth opening 3155 of the mouth portion3105 may be located in the base 3135. Pressurized respiratory gas in theplenum 3200 may be discharged through the fourth opening 3155 to thenasal portion 3110.

FIG. 8 illustrates the fourth opening 3155 being substantiallytrapezoidal shaped. However, the fourth opening 3155 may have any shapethat allows the flow of pressurized respiratory gas to be dischargedfrom the plenum 3200. In addition, it is contemplated that the rimaround the fourth opening 3155 may be saddle shaped, while the outer rim3145 may include alternating cylinder and dome shaped regions. A troughmay be formed between the saddle shaped rim and the dome and cylindershaped outer rim. Alternatively, the base 3135 of the receptacle 3130may be flat and/or planar so that the receptacle 3130 does not have atrough. The shape of the receptacle 3130 may allow the nasal portion3110 to be positioned closer to a central part of the main body 3010 toform a more compact structure when the nasal portion 3110 is secured tothe mouth portion 3105.

It is contemplated that the wall 3211 (or shell) may extend over asuperior side of the mouth portion 3105 so that the wall 3211 forms thereceptacle 3130 and includes the fourth opening 3155. The shapesdescribed above would also apply to a fourth opening 3155 and receptacle3130 formed by the wall 3211.

The nasal portion 3110 may comprise a nasal base 3160 and a pair ofnasal pillows 3165 extending from the nasal base 3160. The nasal base3160 may be a hollow body that forms a nasal plenum 3170. In addition,at least part of the nasal base 3160 may have a shape that iscomplementary to the shape of the at least one side wall 3140 of thereceptacle 3130. It is contemplated that the nasal base 3160 may beconstructed from a soft, flexible, resilient material such as, forexample, silicone. As such, the nasal base 3160 may be configured toconform to the shape of the at least one side wall 3140 of thereceptacle 3130 when the nasal base 3160 is received within thereceptacle 3130.

The central portions of the nasal base 3160 (including the portionbetween the nasal pillows 3165) may have a saddle shape. In addition,the lateral sides of the nasal base 3160 may be dome shaped.

An inlet opening 3175 may be located on a side of the nasal base 3160that is opposite the nasal pillows 3165. It is contemplated that theinlet opening 3175 may have a similar or the same shape and size as thefourth opening 3155 in the mouth portion 3105. In addition, the inletopening 3175 may be aligned with the fourth opening 3155 when the nasalportion 3110 is secured to the mouth portion 3105 so that pressurizedrespiratory gas in the plenum 3200 may flow through the fourth opening3155 to the inlet opening 3175 and into the nasal plenum 3170. Also, thesurface of the nasal base 3160 around the inlet opening 3175 may beplanar or flat.

The pair of nasal pillows 3165 may form a seal with an interior of thepatient's nares and/or an underside of the patient's nose. In addition,the pair of nasal pillows 3165 may be integrally formed with the nasalbase 3160. Alternatively, each nasal pillow 3165 may be removable fromthe nasal base 3160. In yet another alternative configuration, the nasalpillows 3165 may be removable from the nasal base 3160 as a unit.

The nasal pillows 3165 may include openings through which thepressurized respiratory gas may be discharged into the patient's nasalpassages. The surface (rim) around the openings in the nasal pillows3165 may be saddle shaped. Also, it is contemplated that the nasalpillows may have a double wall structure (as illustrated in FIGS. 9, 13,21, and 22 ) or a single wall structure (not shown).

The nasal portion 3110 may be secured to the mouth portion 3105 by anynumber of methods. For example, the nasal portion 3110 may be secured tothe mouth portion 3105 by way of a clip or a magnetic connection.

4.3.3.1 Clip Connection

In one aspect of the technology illustrated in FIGS. 9-18 , the nasalportion 3110 may be secured to the mouth portion 3105 by way of a clip(or cushion clip) 6000. The clip 6000 may be in the form of a tubularstructure that is open at both ends. The clip 6000 may have a lumen (orbore) 6005 extending from one end to the other and forming a gas flowpath through the clip 6000. The lumen may have a central longitudinalaxis 6007. In addition, the clip may be formed from a rigid and/ormolded material such, for example, plastic. Alternatively, the clip 6000may be formed from a flexible material such as, for example, silicone.

The clip 6000 may be secured to the nasal base 3160 by way of aninterference fit in which structures on the clip 6000 and the nasal base3160 may interlock. For example, a portion of the clip 6000 may beinserted inside the nasal base 3160 so that one or more features on theouter surface of the clip 6000 may interlock with one or more featureson an interior surface of the nasal base 3160. It is contemplated thatthe clip 6000 may be secured to the nasal base 3160 by any other methodsuch as, for example, a threaded connection, a bayonet connection, amagnetic connection, a snap-fit connection, etc. The clip 6000 may alsobe secured to the nasal base 3160 by any combination of the connectiontypes listed above. In addition, for configurations in which the clip6000 is permanently attached to the nasal base 3160, the clip 6000 maybe attached to the nasal base 3160 by way of adhesive, chemical bonding,co-molding, or any other permanent connection method.

It is contemplated that in some configurations a rim of the inletopening 3175 of the nasal base 3160 may form part of the interferencefit and may be in the form of an inwardly projecting flange (or lip)3180. The flange 3180 may be tapered toward a free end of the flange3180 so that the flange 3180 is thickest closest to its base at a sidewall 3182 and is thinnest at its free end.

In addition, as can be seen in FIG. 9A, the flange 3180 may have anasymmetrical cross-sectional shape. In particular, the flange 3180 mayhave a first side 3185 facing toward the nasal pillows 3165 and a secondside 3190 facing away from the nasal pillows 3165. The first side 3185may form a first angle α with a line 3195 that extends through thefurthest extent of the flange 3180 and is perpendicular with the sidewall 3182. The second side 3190 may form a second angle β with the line3195. The angle α may be smaller than the angle β so that the taper ofthe second side 3190 is greater than the taper of the first side 3185.

The clip 6000 may be bisected by a middle flange 6010 on an exteriorsurface of the clip 6000 that extends radially away from the lumen 6005and around a perimeter of the clip 6000. In addition, the clip 6000 maycomprise a first end flange (or nasal end flange) 6015 on one side ofthe middle flange 6010 and a second end flange (or mouth end flange)6020 on the other side of the middle flange 6010. The middle flange 6010and the first end flange 6015 together may form a first channel (orfirst groove or first trench) 6025 configured to receive the flange 3180of the nasal base 3160. In addition, the middle flange 6010 and thesecond end flange 6020 together may form a second channel (or secondgroove or second trench) 6030 configured to receive a part of thereceptacle 3130.

The middle flange 6010 may be a continuous structure that fullyencircles the lumen 6005. Alternatively, the middle flange 6010 may be adiscontinuous structure and/or may extend only partly around the lumen6005 (e.g., partially encircle the lumen 6005). In addition, the middleflange 6010 may be tapered toward a free end of the middle flange 6010.Accordingly, the middle flange 6010 may be thickest closest to the lumen6005 and may be thinnest at its free end.

As can be seen in FIG. 9B, the middle flange 6010 may have anasymmetrical cross-sectional shape. In particular, the middle flange6010 may have a first side (or nasal portion facing side) 6035 formingpart of the first channel 6025. The middle flange 6010 may have a secondside (or mouth portion facing side) 6040 forming part of the secondchannel 6030. The first side 6035 may form an angle γ with a line 6045that extends through the free end of the middle flange 6010 and isperpendicular with a side wall 6047 of the lumen 6005. The second side6040 may form an angle δ with the line 6045. The angle γ may be greaterthan the angle δ so that the taper of the first side 6035 is greaterthan the taper of the second side 6040.

Similar to the middle flange 6010, the first end flange 6015 may also betapered (FIG. 9C). In particular, a channel side 6050 of the first endflange 6015 may form an angle ϕ with a line 6055 that extends throughthe furthest extend of the first end flange 6015 and is perpendicularwith the side wall 6047. The angle of taper for the channel side 6050may match the angle of taper of the first side 3185 of the flange 3180.In addition, the angle of taper of the first side 6035 of the middleflange 6010 may match the angle of taper of the second side 3190 of theflange 3180. That way, the shape of the first channel 6025 of the clip6000 may be complimentary to the shape of the flange 3180.

When the clip 6000 is inserted into the nasal base 3160 to connect theclip 6000 to the nasal base 3160, the flange 3180 may be received withinthe first channel 6025. Because the shape of the first channel 6025 maybe complimentary to the shape of the flange 3180, the flange 3180 mayform an air-tight seal with the first end flange 6015 and the middleflange 6010. In addition, the flange 3180 may resist movement of theclip 6000 relative to the nasal base 3160 along the central longitudinalaxis 6007 (i.e., axial movement of the clip 6000).

It should be understood that the asymmetrical cross-section of theflange 3180 allows the clip 6000 to be pushed into the nasal base 3160with less force than is necessary to remove the clip 6000 from the nasalbase 3160. In other words, the flange 3180 may provide more resistanceto the removal of the clip 6000 from the nasal base 3160 than theinsertion of the clip 6000 into the nasal base 3160. In particular, thelarger taper angle of the second side 3190 of the flange 3180 may offerless resistance to the insertion (inward movement) of the first endflange 6015 of the clip 6000 than the resistance offered by the firstside 3185 to the removal (outward movement) of the first end flange 6015of the clip 6000.

It is contemplated that the clip 6000 may optionally include a pair ofwings (or extensions or supplemental flanges) 6060 that may enhance theretention force keeping the clip 6000 secured to the nasal base 3160. Inone example, a form of the clip 6000 without the wings 6060 may haveretention force between 10 and 12 N. In other words it may take at least10 to 12 N to remove the clip 6000 without wings 6060 from the nasalbase 3160. On the other hand, a form of the clip 6000 with wings 6060may have a retention force between 19 and 20 N. In other words, it maytake at least 19 to 20 N to remove the clip 6000 with wings 6060 fromthe nasal base 3160. Thus, in the example provided above, the wings 6060increased the retention force keeping the clip 6000 secured to the nasalbase 3160 by as much as 100% (i.e., doubled the retention force).

As can be seen in FIG. 14 , each wing 6060 may extend from the nasalpillow facing side 6065 of the first end flange 6015. In addition, thewings 6060 may be positioned on opposite lateral sides of the clip 6000so that the lumen 6005 intervenes between the two wings 6060. The base6070 of each wing 6060 may extend around one side of the lumen 6005 froman anterior side of the first end flange 6015 to a posterior side of thefirst end flange 6015. As a result, the ends 6075 of the base 6070 maybe closest to the central longitudinal axis 6007 of the lumen 6005,while a middle part of the base 6070 may be furthest from the centrallongitudinal axis 6007 of the lumen 6005. In addition, the extent towhich each wing 6060 projects from the first end flange 6015 maygradually increase from each end 6075 of the base 6070 to a maximumdistance at a middle portion of the wing 6060.

Each wing 6060 may be oriented so that each wing 6060 extends from thefirst end flange 6015 in an axial and lateral direction so that eachwing 6060 extends beyond the first end flange 6015 both laterally andaxially. In addition, the outer surfaces of the wings 6060 may engagethe lateral sides of the inner surface of the nasal plenum 3170. It iscontemplated that the shape of the outer surfaces of the wings 6060 maybe complimentary to the shape of the inner surface of the nasal plenum3170. In addition, the wings 6060 may remain unfixed (i.e., movable)relative to the sides of the nasal plenum 3170 even after the clip 6000is secured to the nasal plenum 3170. For example, the wings 6060 mayslide along the inner surface of the nasal plenum 3170 if the nasalplenum 3170 is compressed and portions of the inner surface of the nasalplenum 3170 move or fold due to the compression of the nasal plenum3170.

The wings 6060 may add rigidity and provide support to the lateral sidesof the nasal plenum 3170 so that the lateral sides of the nasal plenum3170 have more rigidity than the central anterior and posterior sides.The height of the wings 6060 as measured from the first end flange 6015may increase toward the lateral sides of the clip 6000 and may decreasetoward the central posterior and central anterior sides of the clip 6000so that the maximum height may be at the furthest lateral extent of thewing 6060. It is contemplated that the increase in height may be gradualand may form a curved shape at an edge of the wing 6060. This way, thenasal plenum 3170 may be more flexible at the central region than at thelateral sides. By limiting the wings 6060 to the lateral sides of thenasal plenum 3170 and by varying the height of the wings 6060, thepatient's comfort may be maintained while also strengthening theconnection between the nasal portion 3110 and the clip 6000. Inparticular, if the wings 6060 were located toward the central portion ofthe nasal plenum 3170 or if the maximum height of the wings 6060 waslocated toward the central portion of the nasal plenum 3170, the wings6060 would be more likely to press against the patient's upper lip ornose tip if the nasal plenum 3170 was compressed. However, since thewings 6060 are located on the lateral sides of the nasal plenum 3170,the wings 6060 are aligned on either side of the patient's nose and areless likely to press against any sensitive portion of the patient'sface.

As illustrated in FIG. 17 , the clip 6000 may similarly be secured tothe mouth portion 3105 by way of an interference fit in which structureson the clip 6000 and the receptacle 3130 may interlock. For example, aportion of the clip 6000 may be inserted inside the plenum 3200 so thatone or more features on the outer surface of the clip 6000 may interlockwith one or more features on a surface of the receptacle 3130. It iscontemplated that the clip 6000 may be secured to the mouth portion 3105by any other method such as, for example, a threaded connection, abayonet connection, a magnetic connection, a snap-fit connection, etc.Also, the clip 6000 may be secured to the mouth portion 3105 by anycombination of the connection types listed above.

It is contemplated that in some configurations a rim of the fourthopening 3155 of the receptacle 3130 may form part of the interferencefit and may be in the form of an inwardly projecting flange (or lip)3197. The flange 3197 may be tapered toward a free end of the flange3197 so that the flange 3197 is thickest closest to its base at the atleast one side wall 3140 and is thinnest at its free end.

4.3.3.2 Magnetic Connection

In another aspect of the technology illustrated in FIGS. 19-23 , thenasal portion 3110 may be secured to the mouth portion 3105 by way of amagnetic connection. The magnetic connection may be in the form of apair of nasal module magnets 7000 located on the nasal base 3160 and apair of receptacle magnets 7005 located in the receptacle 3130. Unlikethe clip connection, the magnetic connection may eliminate a rigid bodybetween the flexible bodies of the nasal portion 3110 and the mouthportion 3105. In other words, the magnetic connection may be a directconnection between flexible bodies.

As illustrated in FIGS. 20 and 21 , the nasal module magnets 7000 may belocated on opposing lateral sides of the nasal base 3160 so that thelumen 6005 intervenes between the nasal module magnets 7000. Inaddition, the nasal module magnets 7000 may be arranged so that one sideof one magnet 7000 having a first polarity (i.e., north or southpolarity) faces the general direction of the side of the other magnet7000 having the opposite polarity. This will help position the nasalportion 3110 in the correct orientation when attached to the mouthportion 3105.

Also, the rim around the inlet opening 3175 may include a lip seal 7010configured to sealingly engage the base 3135 of the receptacle 3130. Itis contemplated that the nasal module magnets 7000 may be overmolded tothe side wall 3182 of the nasal base 3160. Alternatively, the nasalmodule magnets 7000 may be secured to the nasal base 3160 by way of anadhesive, a mechanical fastener, or any other method that can secure thenasal module magnets 7000 to the nasal base 3160.

As illustrated in FIGS. 22 and 23 , the receptacle magnets 7005 may belocated on opposing lateral sides of the receptacle 3130 so that whenthe nasal portion 3110 is received within the receptacle 3130, the nasalbase 3160 intervenes between the receptacle magnets 7005. In addition,similar to the nasal module magnets 7000, the receptacle magnets 7005may be arranged so that one side of one magnet 7005 having a firstpolarity (i.e., north or south polarity) faces the general direction ofthe side of the other magnet 7005 having the opposite polarity. Thiswill help position the nasal portion 3110 in the correct orientationwhen attached to the mouth portion 3105.

Also, the shape of the receiving space 3150 and the shape of the nasalbase 3160 may be complimentary so that when the nasal base 3160 isreceived in the receiving space 3150 in the correct orientation, eachnasal module magnet 7000 is automatically aligned with a correspondingone of the receptacle magnets 7005.

It is contemplated that the receptacle magnets 7005 may be overmolded tothe at least one side wall 3140 of the receptacle 3130. Alternatively,the receptacle magnets 7005 may be secured to the mouth portion 3105 byway of an adhesive, a mechanical fastener, or any other method that cansecure the receptacle magnets 7005 to the mouth portion 3105.

When the nasal base 3160 is fully received within the receptacle 3130,the lip seal 7010 may engage with the rim of the fourth opening 3155 toform a seal. The lip seal 7010 may be below the nasal module magnets7000 and the receptacle magnets 7005 when the nasal base 3160 is fullyreceived within the receptacle 3130. In addition, the nasal modulemagnets 7000 may be positioned between the receptacle magnets. It shouldbe understood that the magnetic force between the nasal module magnets7000 and the receptacle magnets 7005 may be sufficient to overcome theair pressure in the plenum 3200 and keep the lip seal 7010 in sealedengagement with the rim of the fourth opening 3155.

As illustrated in FIG. 24 , the magnets 7000, 7005 may have a core 7015in the form of a ring magnet. An outside diameter od of the core 7015may be about 7 mm. An inner diameter id of the core 7015 may be about2.5 mm. In addition, a thickness t of the core 7015 may be about 2 mm.Although the core 7015 is illustrated as a ring magnet, the core 7015may have other shapes such as for example, a disc, a plate, or any othershape that allows for the sealed attachment of the nasal portion 3110 tothe mouth portion 3105. In addition, the magnets 7000, 7005 may have asilicone rubber covering 7020 that is overmolded onto the core 7015. Thesilicone rubber covering 7020 may have a thickness of about 0.5 mm. Itshould be understood that the term “about” as used to describe the abovedimensions allows for manufacturing tolerances.

It is contemplated that each of the nasal module magnets 7000 may have adifferent polarity. Similarly, each of the receptacle magnets 7005 mayhave a different polarity. Accordingly, if the nasal portion 3110 isinserted into the receptacle 3130 in the wrong orientation, a repellentmagnetic force would prevent the nasal portion 3110 from being securedto the mouth portion 3105. It is contemplated that the magnets may bepolarized and magnetized prior to or after being overmolded to the nasalportion 3110 or the mouth portion 3105.

4.3.3.3 Alignment Indicator

As illustrated in FIG. 6 , the mouth portion 3105 may have a printedindicia 8000 located adjacent a rim of the receptacle 3130. At the sametime, the nasal base 3160 may have a printed indicia 8005 positioned toalign with the printed indicia 8000 when the nasal portion 3110 iscorrectly oriented within the receptacle 3130.

It is contemplated that the clip 6000 may have a keyed connection withthe receptacle 3130. In particular, the clip 6000 may have anindentation or notch 8010 that is shaped complementary to a tab or rib8015 located on a rim of the fourth opening 3155. The tab 8015 mayprevent the clip 6000 from being secured to the receptacle 3130 if thenasal portion 3110 is positioned within the receptacle 3130 in the wrongorientation. Alternatively, the rib 8015 may be located on the clip 6000and the indentation 8010 may be in the rim of the fourth opening 3155.

4.3.4 Positioning and Stabilising Structure

The seal-forming structure 3100 of the patient interface 3000 of thepresent technology may be held in sealing position in use by thepositioning and stabilising structure 3300.

In one form the positioning and stabilising structure 3300 provides aretention force at least sufficient to overcome the effect of thepositive pressure in the plenum chamber 3200 to lift off the face.

In one form the positioning and stabilising structure 3300 provides aretention force to overcome the effect of the gravitational force on thepatient interface 3000.

In one form the positioning and stabilising structure 3300 provides aretention force as a safety margin to overcome the potential effect ofdisrupting forces on the patient interface 3000, such as from tube drag,or accidental interference with the patient interface.

In one form of the present technology, a positioning and stabilisingstructure 3300 is provided that is configured in a manner consistentwith being worn by a patient while sleeping. In one example thepositioning and stabilising structure 3300 has a low profile, orcross-sectional thickness, to reduce the perceived or actual bulk of theapparatus. In one example, the positioning and stabilising structure3300 comprises at least one strap having a rectangular cross-section. Inone example the positioning and stabilising structure 3300 comprises atleast one flat strap.

In one form of the present technology, a positioning and stabilisingstructure 3300 is provided that is configured so as not to be too largeand bulky to prevent the patient from lying in a supine sleepingposition with a back region of the patient's head on a pillow.

In one form of the present technology, a positioning and stabilisingstructure 3300 is provided that is configured so as not to be too largeand bulky to prevent the patient from lying in a side sleeping positionwith a side region of the patient's head on a pillow.

In one form of the present technology, a positioning and stabilisingstructure 3300 is provided with a decoupling portion located between ananterior portion of the positioning and stabilising structure 3300, anda posterior portion of the positioning and stabilising structure 3300.The decoupling portion does not resist compression and may be, e.g. aflexible or floppy strap. The decoupling portion is constructed andarranged so that when the patient lies with their head on a pillow, thepresence of the decoupling portion prevents a force on the posteriorportion from being transmitted along the positioning and stabilisingstructure 3300 and disrupting the seal.

In one form of the present technology, a positioning and stabilisingstructure 3300 comprises a strap constructed from a laminate of a fabricpatient-contacting layer, a foam inner layer and a fabric outer layer.In one form, the foam is porous to allow moisture, (e.g., sweat), topass through the strap. In one form, the fabric outer layer comprisesloop material to engage with a hook material portion.

In certain forms of the present technology, a positioning andstabilising structure 3300 comprises a strap that is extensible, e.g.resiliently extensible. For example the strap may be configured in useto be in tension, and to direct a force to draw a seal-forming structureinto sealing contact with a portion of a patient's face. In an examplethe strap may be configured as a tie.

In one form of the present technology, the positioning and stabilisingstructure comprises a first tie, the first tie being constructed andarranged so that in use at least a portion of an inferior edge thereofpasses superior to an otobasion superior of the patient's head andoverlays a portion of a parietal bone without overlaying the occipitalbone.

In one form of the present technology suitable for a nasal-only mask orfor a full-face mask, the positioning and stabilising structure includesa second tie, the second tie being constructed and arranged so that inuse at least a portion of a superior edge thereof passes inferior to anotobasion inferior of the patient's head and overlays or lies inferiorto the occipital bone of the patient's head.

In one form of the present technology suitable for a nasal-only mask orfor a full-face mask, the positioning and stabilising structure includesa third tie that is constructed and arranged to interconnect the firsttie and the second tie to reduce a tendency of the first tie and thesecond tie to move apart from one another.

In certain forms of the present technology, a positioning andstabilising structure 3300 comprises a strap that is bendable and e.g.non-rigid. An advantage of this aspect is that the strap is morecomfortable for a patient to lie upon while the patient is sleeping.

In certain forms of the present technology, a positioning andstabilising structure 3300 comprises a strap constructed to bebreathable to allow moisture vapour to be transmitted through the strap,

In certain forms of the present technology, a system is providedcomprising more than one positioning and stabilizing structure 3300,each being configured to provide a retaining force to correspond to adifferent size and/or shape range. For example the system may compriseone form of positioning and stabilizing structure 3300 suitable for alarge sized head, but not a small sized head, and another suitable for asmall sized head, but not a large sized head.

4.3.4.1 Headgear Tubing

In some forms of the present technology, the positioning and stabilisingstructure 3300 comprises one or more tubes 3350 that deliver pressurisedair received from a conduit forming part of the air circuit 4170 fromthe RPT device to the patient's airways, for example through the mainbody 3010. In the form of the present technology illustrated in FIG. 6 ,the positioning and stabilising structure 3300 may comprise two tubes3350 that deliver air to the seal-forming structure 3100 from the aircircuit 4170. The tubes 3350 may be an integral part of the positioningand stabilising structure 3300 of patient interface 3000 to position andstabilise the seal-forming structure 3100 of the patient interface tothe appropriate part of the patient's face (for example, the nose and/ormouth). This may allow the conduit of air circuit 4170 to provide theflow of pressurised air to connect to a connection port 3600 of thepatient interface in a position other than in front of the patient'sface which may be unsightly to some people. While a pair of tubes 3350have some advantages (described below), in some examples, thepositioning and stabilising structure 3300 may comprise only a singletube 3350 configured to overlie the patient's head on one side. A strapor other stabilising component may be provided to the other side of thepatient's head between the top end of the single tube 3350 and theseal-forming structure 3100, to provide balanced forces on theseal-forming structure 3100.

Since air can be contained and passed through headgear tubing 3350 inorder to deliver pressurised air from the air circuit 4170 to thepatient's airways, the positioning and stabilising structure 3300 may bedescribed as being inflatable. It will be understood that an inflatablepositioning and stabilising structure 3300 does not require allcomponents of the positioning and stabilising structure 3300 to beinflatable. For example, in the example shown in FIG. 6 , thepositioning and stabilising structure 3300 comprises the headgear tubing3350, which is inflatable, and the straps 3310, which are notinflatable.

In certain forms of the present technology, the patient interface 3000may comprise a connection port 3600 located proximal a top, side or rearportion of a patient's head. For example, in the form of the presenttechnology illustrated in FIG. 6 , the connection port 3600 is locatedon top of the patient's head. In this example the patient interface 3000comprises an elbow 3610 to which the connection port 3600 is provided.The elbow 3610 may swivel with respect to the positioning andstabilising structure 3300 in order to decouple movement of a conduitconnected to the connection port 3600 from the positioning andstabilising structure 3300. Additionally, or alternatively, a conduitconnected to the connection port 3600 may swivel with respect to theelbow 3610. In the illustrated example, elbow 3610 comprises aswivelling conduit connector to which a conduit of the air circuit 4170is able to connect such that the conduit can rotate about itslongitudinal axis with respect to the elbow 3610.

Patient interfaces in which the connection port is not positioned infront of the patient's face may be advantageous as some patients find aconduit that connects to a patient interface in front of the face to beunsightly and obtrusive. For example, a conduit connecting to a patientinterface in front of the face may be prone to being tangled up inbedclothes or bed linen, particularly if the conduit extends downwardlyfrom the patient interface in use. Forms of the technology with apatient interface with a connection port positioned proximate the top ofthe patient's head in use may make it easier or more comfortable for apatient to lie or sleep in one or more of the following positions: in aside or lateral position; in a supine position (i.e. on their back,facing generally upwards); and in a prone position (i.e. on their front,facing generally downwards). Moreover, connecting a conduit to the frontof a patient interface may exacerbate a problem known as tube drag,wherein the conduit may provide an undesired drag force upon the patientinterface thereby causing dislodgement away from the face.

In the form of the present technology illustrated in FIG. 6 , thepositioning and stabilising structure 3300 comprises two tubes 3350,each tube 3350 being positioned in use on a different side of thepatient's head and extending across the respective cheek region, abovethe respective ear (superior to the otobasion superior on the patient'shead) to the elbow 3610 on top of the head of the patient 1000. Thisform of technology may be advantageous because, if a patient sleeps withtheir head on its side and one of the tubes is compressed to block orpartially block the flow of gas along the tube, the other tube remainsopen to supply pressurised gas to the patient. In other examples of thetechnology, the patient interface 3000 may comprise a different numberof tubes, for example one tube, or three or more tubes. In one examplein which the patient interface has one tube 3350, the single tube 3350is positioned on one side of the patient's head in use (e.g. across onecheek region) and a strap forms part of the positioning and stabilisingstructure 3300 and is positioned on the other side of the patient's headin use (e.g. across the other region) to assist in securing the patientinterface 3000 on the patient's head.

In the form of the technology shown in FIG. 6 the two tubes 3350 arefluidly connected at their upper ends to each other and to connectionport 3600. In one embodiment, the two tubes are integrally formed whilein other embodiments the tubes are separate components that areconnected together in use and may be disconnected, for example forcleaning or storage. Where separate tubes are used they may beindirectly connected together, for example each may be connected to aT-shaped conduit having two conduit arms each fluidly connectable to thetubes 3350 and a third conduit arm or opening acting as the connectionport 3600 and connectable in use to the air circuit 4170. The connectionport 3600 may comprise an elbow 3610 received in fluid connection at thecentre of two integrally formed tubes 3350.

The tubes 3350 may be formed of a semi-rigid material such as anelastomeric material, e.g. silicone. For example, the tubes 3350, fromthe left-side non-extendable tube section 3363 to the right sidenon-extendable tube section 3363, may be formed (e.g., by molding) froma single homogeneous piece of material, such as silicone. The tubes mayhave a natural, preformed shape and be able to be bent or moved intoanother shape if a force is applied to the tubes. For example, the tubesmay be generally arcuate or curved in a shape approximating the contoursof a patient's head between the top of the head and the nasal or oralregion.

As described in U.S. Pat. No. 6,044,844, the contents of which areincorporated herein, the tubes 3350 may be crush resistant to avoid theflow of breathable gas through the tubes if either is crushed duringuse, for example if it is squashed between a patient's face and pillow.Crush resistant tubes may not be necessary in all cases as thepressurised gas in the tubes may act as a splint to prevent or at leastrestrict crushing of the tubes 3350 during use. A crush resistant tubemay be advantageous where only a single tube 3350 is present as if thesingle tube becomes blocked during use the flow of gas would berestricted and therapy will stop or reduce in efficacy.

In certain forms of the technology, one or more portions of the tubes3350 may be rigidised by one or more rigidising or stiffening elements.Examples of rigidising elements include: sections of the tubes 3350 thatare comparatively thicker than other sections; sections of the tubes3350 that are formed from a material that is comparatively more rigidthat the material forming other sections; and a rigid member attached tothe inside, outside or embedded in a section of tube. The use of suchrigidising elements helps to control how the positioning and stabilisingstructure 3300 will function in use, for example where the tubes 3350 ismore likely to deform if forces are applied to them and where the shapeof the tubes 3350 is more likely to be maintained if forces are applied.The selection of where such rigidising elements are positioned in thetubes 3350 can therefore help to promote comfort when the patientinterface 3000 is worn and can help to maintain a good seal at theseal-forming structure 3100 during use. Rigidising or stiffeningelements may be in positioning and stabilising structures 3300 which areconfigured to support relatively heavy seal-forming structures such asfull face or oro-nasal cushion assemblies.

The tubes 3350 in the form of the technology shown in FIG. 6 have alength of between 15 and 30 cm each, for example between 20 and 27 cmeach. In one example each of the tubes are around 26 cm long. In anotherexample each of the tubes is around 23 cm long. The length of the tubesis selected to be appropriate for the dimensions of the heads of typicalpatients, for example the distance between the region proximate the topof the head where the upper end of the tubes 3350 are situated, and theregion proximate the openings to the patient's airways at which thelower end of the tubes 3350 connect to the wall 3211 when following agenerally arcuate path down the sides of the heads and across thepatient's cheek region such as is shown in FIG. 6 . As described in moredetail below, the patient interface 3000 is configured so that thelength of the tubes 3350 can be varied in some forms of the technologyand the above lengths may apply to the tube in a contracted, stretchedor neutral state. It will be appreciated that the length of the tubes3350 will depend on the length of other components in the patientinterface 3000, for example the length of arms of a T-shaped conduit towhich the upper ends of tubes 3350 connect and/or the size of the plenumchamber 3200.

4.3.4.2 Headgear Straps

In certain forms of the present technology, the positioning andstabilising structure 3300 comprises at least one headgear strap actingin addition to the tubes 3350 to position and stabilise the seal-formingstructure 3100 in sealing position at the entrance to the patient'sairways. As shown in FIG. 6 , the patient interface 3000 comprises astrap 3310 forming part of the positioning and stabilising structure3300. The strap 3310 may be known as a back strap or a rear headgearstrap, for example. In other examples of the present technology, one ormore further straps may be provided. For example, a patient interface3000 according to an example of the present technology having a fullface or oro-nasal cushion module may have a second, lower, strapconfigured to overlie the back of the patient's neck.

4.3.5 Vent

In one form, the patient interface 3000 includes a vent 3400 constructedand arranged to allow for the washout of exhaled gases, e.g. carbondioxide.

In certain forms the vent 3400 is configured to allow a continuous ventflow from an interior of the plenum chamber 3200 to ambient whilst thepressure within the plenum chamber is positive with respect to ambient.The vent 3400 is configured such that the vent flow rate has a magnitudesufficient to reduce rebreathing of exhaled CO2 by the patient whilemaintaining the therapeutic pressure in the plenum chamber in use.

One form of vent 3400 in accordance with the present technologycomprises a plurality of holes, for example, about 20 to about 80 holes,or about 40 to about 60 holes, or about 45 to about 55 holes.

The vent 3400 may be located in the plenum chamber 3200. Alternatively,the vent 3400 is located in a decoupling structure, e.g., a swivel.

4.3.5.1 Single Use Vent

In one aspect of the technology illustrated in FIGS. 6, 7, 19, and 25-36, the vent 3400 may allow for the washout of exhaled gases through thethird opening 3125 of the mouth portion 3105. In addition, the vent 3400may be positioned away from any air inlet into the plenum 3200. Forexample, the vent 3400 may be positioned within the third opening 3125of the mouth portion 3105. Alternatively, the vent 3400 may bepositioned in another opening (not shown) in the wall 3211 that mayallow for the washout of exhaled gases through the wall 3211.Preferably, the vent 3400 may be configured to be permanently retainedwithin the third opening 3125. However, it is contemplated that the vent3400 may be removable from the third opening 3125 for cleaning.

The vent 3400 may be an assembly comprising a main body 3405, a cover3410, and a diffuser 3415 sandwiched between the main body 3405 and thecover 3410.

The main body 3405 may be formed of a rigid material such as plastic andmay be the part of the vent 3400 that anchors the vent 3400 to the mouthportion 3105. The main body 3405 may comprise a frame 3420 with featuresthat secure the vent 3400 to the mouth portion 3105 and a receptacle (orretaining portion) 3425 with a receiving space that is bound by theframe 3420.

The frame 3420 may include a first flange 3430 that extends around aperimeter of the frame 3420. A second flange 3435 may be locatedopposite the first flange 3430. The first flange 3430 and the secondflange 3435 may together form a channel 3440. When the vent 3400 isassembled to the mouth portion 3105, at least a portion of the rim ofthe third opening 3125 may be received within the channel 3440 so thatthe first flange 3430 and the second flange 3435 may hold the frame 3420in place within the third opening 3125. In addition, the engagement ofthe first flange 3430 and the second flange 3435 with the rim of thethird opening 3125 may form a seal so that the exhaled gas may flowthrough the vent 3400 and not around the vent 3400.

In addition, it is contemplated that there may be one or more gaps (ornotches) 3445 in the first flange 3430 and/or the second flange 3435.The gaps 3445 may be positioned, sized, and shaped to be complimentaryto a tab 3450 extending from the rim of the third opening 3125. The tab3450 may be received by corresponding one of the gaps 3445 when theframe 3420 is in the correct orientation. The tab 3450 may prevent theframe 3420 from being received within the third opening 3125 when theframe 3420 is in the wrong orientation. It should be understood that thelocations of the gaps 3445 and the tabs 3450 may be swapped so that thegaps 3445 are located on the rim of the third opening 3125 and the tabs3450 are located on the first flange 3430 and/or the second flange 3435.It is further contemplated that the vent 3400 may have other alignmentindicators such as printed indicia.

The receptacle 3425 may include a vent wall 3455 with a plurality ofvent holes 3460. The receptacle 3425 may also include one or more sidewalls 3465 that extend from a perimeter of the vent wall 3455 toward thesecond flange 3435. In addition, a pair of anchor blocks 3470 may belocated on opposing lateral sides of the receptacle 3425.

It is contemplated that the vent wall 3455 is contoured so that a sideof the vent wall 3455 facing the interior of the receptacle 3425 has aconvex shape, and an opposite side of the vent wall 3455 is concave. Theplurality of vent holes 3460 may be arranged in any pattern. Forexample, as shown in FIG. 33 , the vent wall 3455 may comprise 16 ventholes 3460 arranged in two rows.

Each vent holes 3460 may be tapered toward the convex side of the ventwall 3455 (i.e., the side facing the receptacle 3425 and facing awayfrom the plenum 3200). In other words, the cross-sectional area of thevent path through each vent hole 3460 may decrease as the vented gasmoves further away from the plenum 3200. Accordingly, each vent hole3460 may have a larger cross-sectional area at the concave side of thevent wall 3455 than the cross-sectional area at the convex side of thevent wall 3455 (i.e., the side facing the plenum 3200). The angle oftaper θ of each vent hole 3460 (the angle formed by the side walls ofthe vent hole 3460) may be between 10 and 35 degrees. For example, theangle of taper θ may be 30.4 degrees or 14.0 degrees. In addition, thediameter D of each vent hole 3460 at the smaller end may be between 0.5and 2 mm. For example, the diameter D may be 0.89, 0.98, 1.17 mm, or1.01 mm. The thickness of the vent wall 3455 (and the height of eachvent hole 3460) H may be between 1.5 and 2.5 mm. For example, thethickness H may be 2.0 mm.

As illustrated in FIG. 28 , each vent hole may flare outward at thelarger side (i.e., side adjacent the plenum 3200). The flared portionsof the vent holes 3460 may have a radius of curvature R between 0.2 mmand 0.4 mm. For example, the radius of curvature may be 0.25 mm or 0.3mm.

The cover 3410 may be secured to the main body 3405 at the anchor blocks3470. The cover 3410 may be secured by way of a friction fit, a snapfit, an adhesive, a mechanical fastener, or any other fastening method.

Each anchor block 3470 may be located at a lateral side of the main body3405 and may include an interfacing surface 3475 that is inside thereceptacle 3425 and is offset from the vent wall 3455. The interfacingsurface 3475 may have an anchor hole (socket) 3480 that receives acorresponding anchor peg (or anchor post) 3485 that extends from cover3410. The anchor hole 3480 may be keyed with the anchor peg 3485. Inother words, the anchor hole 3480 may be shaped complimentarily to theshape of the anchor peg 3485. It is contemplated that the anchor hole3480 may extend into the anchor block 3470 as far as the channel 3440(FIG. 30 ). It is further contemplated that the anchor hole 3480 mayextend beyond the channel 3440 and may narrow toward the bottom of theanchor hole 3480 (FIG. 36 ). Extending and narrowing the anchor hole3480 may allow for more surface contact and may allow the anchor pegs3485 of the cover 3410 to fit more tightly and become more edged in theanchor holes 3480, thereby increasing the retaining force acting on theanchor pegs 3485. In addition, each anchor hole 3480 may have adifferent shape and/or size so that the anchor pegs 3485 cannot beinserted into the anchor holes 3480 unless the cover 3410 is in thecorrect orientation.

As shown in FIGS. 27 and 33 , the vent wall 3455 may include a firstsupport strip 3490 across a lateral length of the vent wall 3455. Thefirst support strip 3490 may extend from one of the anchor blocks 3470to the other anchor block 3470. A pair of second support strips 3495 mayposition on opposite sides of the first support strip 3490 and mayextend in a direction perpendicular to the first support strip 3490. Thediffuser 3415 may rest on the first support strip 3490 and the secondsupport strips 3495 when the diffuser 3415 is received within thereceptacle 3425. Thus, the diffuser 3415 may be spaced away from thevent wall 3455 so that a space is maintained between the diffuser 3415and the vent wall 3455. The first support strip 3490 and the pair ofsupport strips 3495 may also have the effect of dividing the air flow asthe vented gas exits the vent holes 3460.

Because exhalation gas has a level of humidity, the diffuser 3415 isprone to getting wet when exhaled gas flows through the diffuser 3415.Spacing the diffuser away from the vent wall 3455 may allow the diffuser3415 to dry between therapy sessions, which in turn may prevent thegrowth of mold, bacteria, or other undesired contaminants.

It is contemplated that the diffuser 3415 may be a continuous body madeof any porous material such as open cell foam, cotton, or any otherfibrous material. It is also contemplated that the diffuser 3415 may behydrophobic or hydrophilic.

As illustrated in FIGS. 25, 27, and 32 , the anchor blocks 3470 extendall the way or almost all of the way to the second flange 3435. It iscontemplated that the depth of the anchor blocks 3470 may be equal to orlarger than the thickness of the diffuser 3415. This way, attaching thecover 3410 to the main body 3405 will not compress the diffuser 3415 orwill not compress the diffuser beyond a desired and/or a predeterminedthreshold so that the air paths within the diffuser 3415 are notrestricted beyond a desired or predetermined limit. In addition, thelateral sides of the diffuser 3415 may be shaped complimentarily to theshape of the anchor blocks 3470 so that the lateral sides of thediffuser 3415 may abut and/or conform to the anchor blocks 3470 withoutbeing compressed more than a desired and/or predetermined amount. Thisway, the anchor blocks 3470 may prevent lateral movement of diffuser3415. Accordingly, the size of the diffuser 3415 may be maximized andthe diffuser 3415 may be fixed in place without compressing the diffuser3415 or without compressing the diffuser 3415 by more than a desiredand/or predetermined amount.

After the diffuser 3415 has been received in the receptacle 3425, thecover may be positioned on the main body 3405 and the anchor holes 3480may receive the anchor pegs 3485 to secure the cover 3410 to the mainbody 3405, thereby locking the diffuser 3415 in place. It should beunderstood that the cover 3410 may be anchored to the main body 3405 atthe lateral sides of the main body 3405 so that the diffuser 3415 ispositioned between the anchor points (or the attachment mechanisms) thatsecure the cover 3410 to the main body 2405.

The cover 3410 may have a solid surface with no holes and may be smallerthan the receptacle 3425. Accordingly, when the cover 3410 is securedthe main body 3405, a gap 3497 is formed between the perimeter of thereceptacle 3425 and the perimeter of the cover 3410. The underside ofthe cover 3410 may also have a plurality of projections 3499. Oneprojection 3499 may extend lengthwise across a central portion of thecover 3410. A pair of projections 3499 may extend widthwise acrosslateral sides of the cover 3410 (or perpendicular to the lengthwiseprojection 3499). It is contemplated that the lengthwise projection 3499may extend from one widthwise projection 3499 to another widthwiseprojection 3499. In addition, the lengthwise projection 3499 may extendacross a center line of the cover 3410. The projections 3499 may havethe effect of compressing the diffuser 3415 to a predetermined extent,thereby compressing the air paths through the diffuser 3415. Theprojections 3499 may also serve as a flow separator to the air flowingthrough the diffuser 3415. Thus, the flow path of exhaled gas from theplenum 3200 may flow through the vent holes 3460, through the diffuser3415, and around the perimeter of the cover 3410. It is contemplatedthat the projections 3499 may have any cross-sectional shape. Forexample, a cross-sectional shape of the projections 3499 may betriangular. It is also contemplated that different projections 3499 mayhave different cross-sectional shapes or the same cross-sectional shape.

4.3.5.2 Multiple Use Vent

In another aspect of the technology illustrated in FIGS. 37-40 , thevent 3400 may allow for the washout of exhaled gases through the thirdopening 3125 of the mouth portion 3105. In addition, the vent 3400 maybe positioned away from any air inlet into the plenum 3200. For example,the vent 3400 may be positioned within the third opening 3125 of themouth portion 3105. Alternatively, the vent 3400 may be positioned inanother opening (not shown) in the wall 3211 that may allow for thewashout of exhaled gases through the wall 3211. Preferably, in thisconfiguration, the vent 3400 may be configured to be removable from thethird opening 3125 for cleaning. However, it is contemplated that thevent 3400 may be permanently retained within the third opening 3125.

The vent 3400 may be a unitary body with a main body 3405 integrallyformed with a cover 3410. In this configuration, the diffuser may beomitted. The vent 3400 may be formed of a rigid material such asplastic. The main body 3405 may be the part of the vent 3400 thatanchors the vent 3400 to the mouth portion 3105.

The main body 3405 may include a first flange 3430 that extends around aperimeter of the main body 3405. A second flange 3435 may be locatedopposite the first flange 3430. The first flange 3430 and the secondflange 3435 may together form a channel 3440. When the vent 3400 isassembled to the mouth portion 3105, at least a portion of the rim ofthe third opening 3125 may be received within the channel 3440 so thatthe first flange 3430 and the second flange 3435 may hold the main body3405 in place within the third opening 3125. In addition, the engagementof the first flange 3430 and the second flange 3435 with the rim of thethird opening 3125 may form a seal so that the exhaled gas may flowthrough the vent 3400 and not around the vent 3400.

In addition, it is contemplated that there may be one or more gaps (ornotches) 3445 in the first flange 3430 and/or the second flange 3435.The gaps 3445 may be positioned, sized, and shaped to be complimentaryto a tab 3450 extending from the rim of the third opening 3125. The tab3450 may be received by corresponding one of the gaps 3445 when theframe 3420 is in the correct orientation. The tab 3450 may prevent theframe 3420 from being received within the third opening 3125 when theframe 3420 is in the wrong orientation. It should be understood that thelocations of the gaps 3445 and the tabs 3450 may be swapped so that thegaps 3445 are located on the rim of the third opening 3125 and the tabs3450 are located on the first flange 3430 and/or the second flange 3435.It is further contemplated that the vent 3400 may have other alignmentindicators such as printed indicia.

The cover 3410 may include a vent wall 3455 with a plurality of ventholes 3460. In addition the vent 3400 may include one or more side walls3465 that extend from a perimeter of the vent wall 3455 toward the firstflange 3430. Accordingly, the cover 3410 may be spaced away from thethird opening 3125 when the vent 3400 is secured to the mouth portion3105.

It is contemplated that the vent wall 3455 may be contoured so that aside of the vent wall 3455 facing the interior of the vent 3400 has aconcave shape, and an opposite side of the vent wall 3455 is convex. Theplurality of vent holes 3460 may be arranged in any pattern. Forexample, as shown in FIG. 37 , the vent wall 3455 may comprise 20 ventholes 3460 with 16 vent holes 3460 arranged in two rows and twoadditional rows of vent holes 3460 (two vent holes 3460 each) arepositioned on opposite sides of the two rows of 16 vent holes 3460.

Each vent holes 3460 may be tapered toward the convex side of the ventwall 3455 (i.e., the side facing away from the third opening 3125). Inother words, the cross-sectional area of the vent path through each venthole 3460 may decrease as the vented gas moves further away from theplenum 3200. Accordingly, each vent hole 3460 may have a largercross-sectional area at the concave side of the vent wall 3455 than thecross-sectional area at the convex side of the vent wall 3455 (i.e., theside facing the plenum 3200). The angle of taper θ of each vent hole3460 (the angle formed by the side walls of the vent hole 3460) may bebetween 10 and 35 degrees. For example, the angle of taper θ may be 30.4degrees or 14.0 degrees. In addition, the diameter D of each vent hole3460 at the smaller end may be between 0.5 and 2 mm. For example, thediameter D may be 0.89, 0.98, 1.17 mm, or 1.01 mm. The thickness of thevent wall 3455 (and the height of each vent hole 3460) H may be between1.5 and 2.5 mm. For example, the thickness H may be 2.0 mm.

As illustrated in FIG. 38 , each vent hole may flare outward at thelarger side (i.e., side adjacent the plenum 3200). The flared portionsof the vent holes 3460 may have a radius of curvature R between 0.2 mmand 0.4 mm. For example, the radius of curvature may be 0.25 mm or 0.3mm.

As discussed above, the cover 3410 may be integrally formed with themain body 3405. In one configuration, the cover 3410 may have a smoothcontinuous surface. However, in another configuration, the outer surfaceof the cover 3410 may have a channel 3498 that completely encircles thearray of vent holes 3460. The channel 3498 may help reduce sink marksthat may form during the manufacturing process.

4.3.6 Decoupling Structure(s)

In one form the patient interface 3000 includes at least one decouplingstructure, for example, a swivel or a ball and socket.

4.3.7 Connection Port

Connection port 3600 allows for connection to the air circuit 4170.

4.3.8 Anti-Asphyxia Valve

In one form, the patient interface 3000 includes an anti-asphyxia valve.

4.3.9 Ports

In one form of the present technology, a patient interface 3000 includesone or more ports that allow access to the volume within the plenumchamber 3200. In one form this allows a clinician to supplysupplementary oxygen. In one form, this allows for the directmeasurement of a property of gases within the plenum chamber 3200, suchas the pressure.

4.4 RPT Device

An RPT device 4000 in accordance with one aspect of the presenttechnology comprises mechanical, pneumatic, and/or electrical componentsand is configured to execute one or more algorithms 4300, such as any ofthe methods, in whole or in part, described herein. The RPT device 4000may be configured to generate a flow of air for delivery to a patient'sairways, such as to treat one or more of the respiratory conditionsdescribed elsewhere in the present document.

In one form, the RPT device 4000 is constructed and arranged to becapable of delivering a flow of air in a range of −20 L/min to +150L/min while maintaining a positive pressure of at least 6 cmH2O, or atleast 10 cmH2O, or at least 20 cmH2O.

The RPT device may have an external housing 4010, formed in two parts,an upper portion 4012 and a lower portion 4014. Furthermore, theexternal housing 4010 may include one or more panel(s) 4015. The RPTdevice 4000 comprises a chassis 4016 that supports one or more internalcomponents of the RPT device 4000. The RPT device 4000 may include ahandle 4018.

The pneumatic path of the RPT device 4000 may comprise one or more airpath items, e.g., an inlet air filter 4112, an inlet muffler 4122, apressure generator 4140 capable of supplying air at positive pressure(e.g., a blower 4142), an outlet muffler 4124 and one or moretransducers 4270, such as pressure sensors 4272 and flow rate sensors4274.

One or more of the air path items may be located within a removableunitary structure which will be referred to as a pneumatic block 4020.The pneumatic block 4020 may be located within the external housing4010. In one form a pneumatic block 4020 is supported by, or formed aspart of the chassis 4016.

The RPT device 4000 may have an electrical power supply 4210, one ormore input devices 4220, a central controller 4230, a therapy devicecontroller 4240, a pressure generator 4140, one or more protectioncircuits 4250, memory 4260, transducers 4270, data communicationinterface 4280 and one or more output devices 4290. Electricalcomponents 4200 may be mounted on a single Printed Circuit BoardAssembly (PCBA) 4202. In an alternative form, the RPT device 4000 mayinclude more than one PCBA 4202.

4.4.1 RPT Device Mechanical & Pneumatic Components

An RPT device may comprise one or more of the following components in anintegral unit. In an alternative form, one or more of the followingcomponents may be located as respective separate units.

4.4.1.1 Air Filter(s)

An RPT device in accordance with one form of the present technology mayinclude an air filter 4110, or a plurality of air filters 4110.

In one form, an inlet air filter 4112 is located at the beginning of thepneumatic path upstream of a pressure generator 4140.

In one form, an outlet air filter 4114, for example an antibacterialfilter, is located between an outlet of the pneumatic block 4020 and apatient interface 3000 or 3800.

4.4.1.2 Muffler(s)

An RPT device in accordance with one form of the present technology mayinclude a muffler 4120, or a plurality of mufflers 4120.

In one form of the present technology, an inlet muffler 4122 is locatedin the pneumatic path upstream of a pressure generator 4140.

In one form of the present technology, an outlet muffler 4124 is locatedin the pneumatic path between the pressure generator 4140 and a patientinterface 3000 or 3800.

4.4.1.3 Pressure Generator

In one form of the present technology, a pressure generator 4140 forproducing a flow, or a supply, of air at positive pressure is acontrollable blower 4142. For example, the blower 4142 may include abrushless DC motor 4144 with one or more impellers. The impellers may belocated in a volute. The blower may be capable of delivering a supply ofair, for example at a rate of up to about 120 litres/minute, at apositive pressure in a range from about 4 cmH2O to about 20 cmH2O, or inother forms up to about 30 cmH2O when delivering respiratory pressuretherapy. The blower may be as described in any one of the followingpatents or patent applications the contents of which are incorporatedherein by reference in their entirety: U.S. Pat. Nos. 7,866,944;8,638,014; 8,636,479; and PCT Patent Application Publication No. WO2013/020167.

The pressure generator 4140 may be under the control of the therapydevice controller 4240.

In other forms, a pressure generator 4140 may be a piston-driven pump, apressure regulator connected to a high pressure source (e.g. compressedair reservoir), or a bellows.

4.4.1.4 Anti-Spill Back Valve

In one form of the present technology, an anti-spill back valve 4160 islocated between the humidifier 5000 and the pneumatic block 4020. Theanti-spill back valve is constructed and arranged to reduce the riskthat water will flow upstream from the humidifier 5000, for example tothe motor 4144.

4.4.2 RPT Device Algorithms

As mentioned above, in some forms of the present technology, the centralcontroller 4230 may be configured to implement one or more algorithms4300 expressed as computer programs stored in a non-transitory computerreadable storage medium, such as memory 4260. The algorithms 4300 aregenerally grouped into groups referred to as modules.

In other forms of the present technology, some portion or all of thealgorithms 4300 may be implemented by a controller of an external devicesuch as the local external device 4288 or the remote external device4286. In such forms, data representing the input signals and/orintermediate algorithm outputs necessary for the portion of thealgorithms 4300 to be executed at the external device may becommunicated to the external device via the local external communicationnetwork 4284 or the remote external communication network 4282. In suchforms, the portion of the algorithms 4300 to be executed at the externaldevice may be expressed as computer programs, such as with processorcontrol instructions to be executed by one or more processor(s), storedin a non-transitory computer readable storage medium accessible to thecontroller of the external device. Such programs configure thecontroller of the external device to execute the portion of thealgorithms 4300.

In such forms, the therapy parameters generated by the external devicevia the therapy engine module 4320 (if such forms part of the portion ofthe algorithms 4300 executed by the external device) may be communicatedto the central controller 4230 to be passed to the therapy controlmodule 4330.

4.5 Air Circuit

An air circuit 4170 in accordance with an aspect of the presenttechnology is a conduit or a tube constructed and arranged to allow, inuse, a flow of air to travel between two components such as RPT device4000 and the patient interface 3000 or 3800.

In particular, the air circuit 4170 may be in fluid connection with theoutlet of the pneumatic block 4020 and the patient interface. The aircircuit may be referred to as an air delivery tube. In some cases theremay be separate limbs of the circuit for inhalation and exhalation. Inother cases a single limb is used.

In some forms, the air circuit 4170 may comprise one or more heatingelements configured to heat air in the air circuit, for example tomaintain or raise the temperature of the air. The heating element may bein a form of a heated wire circuit, and may comprise one or moretransducers, such as temperature sensors. In one form, the heated wirecircuit may be helically wound around the axis of the air circuit 4170.The heating element may be in communication with a controller such as acentral controller 4230. One example of an air circuit 4170 comprising aheated wire circuit is described in U.S. Pat. No. 8,733,349, which isincorporated herewithin in its entirety by reference.

4.6 Humidifier 4.6.1 Humidifier Overview

In one form of the present technology there is provided a humidifier5000 (e.g. as shown in FIG. 5A) to change the absolute humidity of airor gas for delivery to a patient relative to ambient air. Typically, thehumidifier 5000 is used to increase the absolute humidity and increasethe temperature of the flow of air (relative to ambient air) beforedelivery to the patient's airways.

The humidifier 5000 may comprise a humidifier reservoir 5110, ahumidifier inlet 5002 to receive a flow of air, and a humidifier outlet5004 to deliver a humidified flow of air. In some forms, as shown inFIG. 5A and FIG. 5B, an inlet and an outlet of the humidifier reservoir5110 may be the humidifier inlet 5002 and the humidifier outlet 5004respectively. The humidifier 5000 may further comprise a humidifier base5006, which may be adapted to receive the humidifier reservoir 5110 andcomprise a heating element 5240.

4.6.2 Humidifier Components 4.6.2.1 Water Reservoir

According to one arrangement, the humidifier 5000 may comprise a waterreservoir 5110 configured to hold, or retain, a volume of liquid (e.g.water) to be evaporated for humidification of the flow of air. The waterreservoir 5110 may be configured to hold a predetermined maximum volumeof water in order to provide adequate humidification for at least theduration of a respiratory therapy session, such as one evening of sleep.Typically, the reservoir 5110 is configured to hold several hundredmillilitres of water, e.g. 300 millilitres (ml), 325 ml, 350 ml or 400ml. In other forms, the humidifier 5000 may be configured to receive asupply of water from an external water source such as a building's watersupply system.

According to one aspect, the water reservoir 5110 is configured to addhumidity to a flow of air from the RPT device 4000 as the flow of airtravels therethrough. In one form, the water reservoir 5110 may beconfigured to encourage the flow of air to travel in a tortuous paththrough the reservoir 5110 while in contact with the volume of watertherein.

According to one form, the reservoir 5110 may be removable from thehumidifier 5000, for example in a lateral direction as shown in FIG. 5Aand FIG. 5B.

The reservoir 5110 may also be configured to discourage egress of liquidtherefrom, such as when the reservoir 5110 is displaced and/or rotatedfrom its normal, working orientation, such as through any aperturesand/or in between its sub-components. As the flow of air to behumidified by the humidifier 5000 is typically pressurised, thereservoir 5110 may also be configured to prevent losses in pneumaticpressure through leak and/or flow impedance.

4.6.2.2 Conductive Portion

According to one arrangement, the reservoir 5110 comprises a conductiveportion 5120 configured to allow efficient transfer of heat from theheating element 5240 to the volume of liquid in the reservoir 5110. Inone form, the conductive portion 5120 may be arranged as a plate,although other shapes may also be suitable. All or a part of theconductive portion 5120 may be made of a thermally conductive materialsuch as aluminium (e.g. approximately 2 mm thick, such as 1 mm, 1.5 mm,2.5 mm or 3 mm), another heat conducting metal or some plastics. In somecases, suitable heat conductivity may be achieved with less conductivematerials of suitable geometry.

4.6.2.3 Humidifier Reservoir Dock

In one form, the humidifier 5000 may comprise a humidifier reservoirdock 5130 (as shown in FIG. 5B) configured to receive the humidifierreservoir 5110. In some arrangements, the humidifier reservoir dock 5130may comprise a locking feature such as a locking lever 5135 configuredto retain the reservoir 5110 in the humidifier reservoir dock 5130.

4.6.2.4 Water Level Indicator

The humidifier reservoir 5110 may comprise a water level indicator 5150as shown in FIG. 5A-5B. In some forms, the water level indicator 5150may provide one or more indications to a user such as the patient 1000or a care giver regarding a quantity of the volume of water in thehumidifier reservoir 5110. The one or more indications provided by thewater level indicator 5150 may include an indication of a maximum,predetermined volume of water, any portions thereof, such as 25%, 50% or75% or volumes such as 200 ml, 300 ml or 400 ml.

4.6.2.5 Heating Element

A heating element 5240 may be provided to the humidifier 5000 in somecases to provide a heat input to one or more of the volume of water inthe humidifier reservoir 5110 and/or to the flow of air. The heatingelement 5240 may comprise a heat generating component such as anelectrically resistive heating track. One suitable example of a heatingelement 5240 is a layered heating element such as one described in thePCT Patent Application Publication No. WO 2012/171072, which isincorporated herewith by reference in its entirety.

In some forms, the heating element 5240 may be provided in thehumidifier base 5006 where heat may be provided to the humidifierreservoir 5110 primarily by conduction as shown in FIG. 5B.

4.7 Glossary

For the purposes of the present technology disclosure, in certain formsof the present technology, one or more of the following definitions mayapply. In other forms of the present technology, alternative definitionsmay apply.

4.7.1 General

Air: In certain forms of the present technology, air may be taken tomean atmospheric air, and in other forms of the present technology airmay be taken to mean some other combination of breathable gases, e.g.oxygen enriched air.

Ambient: In certain forms of the present technology, the term ambientwill be taken to mean (i) external of the treatment system or patient,and (ii) immediately surrounding the treatment system or patient.

For example, ambient humidity with respect to a humidifier may be thehumidity of air immediately surrounding the humidifier, e.g. thehumidity in the room where a patient is sleeping. Such ambient humiditymay be different to the humidity outside the room where a patient issleeping.

In another example, ambient pressure may be the pressure immediatelysurrounding or external to the body.

In certain forms, ambient (e.g., acoustic) noise may be considered to bethe background noise level in the room where a patient is located, otherthan for example, noise generated by an RPT device or emanating from amask or patient interface. Ambient noise may be generated by sourcesoutside the room.

Automatic Positive Airway Pressure (APAP) therapy: CPAP therapy in whichthe treatment pressure is automatically adjustable, e.g. from breath tobreath, between minimum and maximum limits, depending on the presence orabsence of indications of SDB events.

Continuous Positive Airway Pressure (CPAP) therapy: Respiratory pressuretherapy in which the treatment pressure is approximately constantthrough a respiratory cycle of a patient. In some forms, the pressure atthe entrance to the airways will be slightly higher during exhalation,and slightly lower during inhalation. In some forms, the pressure willvary between different respiratory cycles of the patient, for example,being increased in response to detection of indications of partial upperairway obstruction, and decreased in the absence of indications ofpartial upper airway obstruction.

Flow rate: The volume (or mass) of air delivered per unit time. Flowrate may refer to an instantaneous quantity. In some cases, a referenceto flow rate will be a reference to a scalar quantity, namely a quantityhaving magnitude only. In other cases, a reference to flow rate will bea reference to a vector quantity, namely a quantity having bothmagnitude and direction. Flow rate may be given the symbol Q. ‘Flowrate’ is sometimes shortened to simply ‘flow’ or ‘airflow’.

In the example of patient respiration, a flow rate may be nominallypositive for the inspiratory portion of a breathing cycle of a patient,and hence negative for the expiratory portion of the breathing cycle ofa patient. Device flow rate, Qd, is the flow rate of air leaving the RPTdevice. Total flow rate, Qt, is the flow rate of air and anysupplementary gas reaching the patient interface via the air circuit.Vent flow rate, Qv, is the flow rate of air leaving a vent to allowwashout of exhaled gases. Leak flow rate, Ql, is the flow rate of leakfrom a patient interface system or elsewhere. Respiratory flow rate, Qr,is the flow rate of air that is received into the patient's respiratorysystem.

Flow therapy: Respiratory therapy comprising the delivery of a flow ofair to an entrance to the airways at a controlled flow rate referred toas the treatment flow rate that is typically positive throughout thepatient's breathing cycle.

Humidifier: The word humidifier will be taken to mean a humidifyingapparatus constructed and arranged, or configured with a physicalstructure to be capable of providing a therapeutically beneficial amountof water (H₂O) vapour to a flow of air to ameliorate a medicalrespiratory condition of a patient.

Leak: The word leak will be taken to be an unintended flow of air. Inone example, leak may occur as the result of an incomplete seal betweena mask and a patient's face. In another example leak may occur in aswivel elbow to the ambient.

Noise, conducted (acoustic): Conducted noise in the present documentrefers to noise which is carried to the patient by the pneumatic path,such as the air circuit and the patient interface as well as the airtherein. In one form, conducted noise may be quantified by measuringsound pressure levels at the end of an air circuit.

Noise, radiated (acoustic): Radiated noise in the present documentrefers to noise which is carried to the patient by the ambient air. Inone form, radiated noise may be quantified by measuring soundpower/pressure levels of the object in question according to ISO 3744.

Noise, vent (acoustic): Vent noise in the present document refers tonoise which is generated by the flow of air through any vents such asvent holes of the patient interface.

Oxygen enriched air: Air with a concentration of oxygen greater thanthat of atmospheric air (21%), for example at least about 50% oxygen, atleast about 60% oxygen, at least about 70% oxygen, at least about 80%oxygen, at least about 90% oxygen, at least about 95% oxygen, at leastabout 98% oxygen, or at least about 99% oxygen. “Oxygen enriched air” issometimes shortened to “oxygen”.

Medical Oxygen: Medical oxygen is defined as oxygen enriched air with anoxygen concentration of 80% or greater.

Patient: A person, whether or not they are suffering from a respiratorycondition.

Pressure: Force per unit area. Pressure may be expressed in a range ofunits, including cmH₂O, g-f/cm² and hectopascal. 1 cmH₂O is equal to 1g-f/cm² and is approximately 0.98 hectopascal (1 hectopascal=100 Pa=100N/m²=1 millibar˜0.001 atm). In this specification, unless otherwisestated, pressure is given in units of cmH₂O.

The pressure in the patient interface is given the symbol Pm, while thetreatment pressure, which represents a target value to be achieved bythe interface pressure Pm at the current instant of time, is given thesymbol Pt.

Respiratory Pressure Therapy: The application of a supply of air to anentrance to the airways at a treatment pressure that is typicallypositive with respect to atmosphere.

Ventilator: A mechanical device that provides pressure support to apatient to perform some or all of the work of breathing.

4.7.1.1 Materials & their Properties

(Durometer Hardness (Indentation Hardness): A material property measuredby indentation of an indentor (e.g. As measured in accordance with ASTMD2240).

-   -   ‘Soft’ materials may include silicone or thermo-plastic        elastomer (TPE), and may, e.g. readily deform under finger        pressure.    -   ‘Hard’ materials may include polycarbonate, polypropylene, steel        or aluminium, and may not e.g. readily deform under finger        pressure.

Silicone or Silicone Elastomer: A synthetic rubber. In thisspecification, a reference to silicone is a reference to liquid siliconerubber (LSR) or a compression moulded silicone rubber (CMSR). One formof commercially available LSR is SILASTIC (included in the range ofproducts sold under this trademark), manufactured by Dow Corning.Another manufacturer of LSR is Wacker. Unless otherwise specified to thecontrary, an exemplary form of LSR has a Shore A (or Type A) indentationhardness in the range of about 35 to about 45.

Polycarbonate: a thermoplastic polymer of Bisphenol-A Carbonate.

4.7.1.2 Mechanics

Axes:

-   -   a. Neutral axis: An axis in the cross-section of a beam or plate        along which there are no longitudinal stresses or strains.    -   b. Longitudinal axis    -   c. Circumferential axis    -   d. Radial axis

Deformation: The process where the original geometry of a member changeswhen subjected to forces, e.g. a force in a direction with respect to anaxis. The process may include stretching or compressing, bending and,twisting.

Stiffness: The ability of a structure or component to resist deformationin response to an applied load. A structure or component may have anaxial stiffness, a bending stiffness, and a torsional stiffness. Astructure or component is said to be stiff when it does not deformeasily when subject to mechanical forces. Stiffness of a structure orcomponent is related to its material properties and its shape. Theinverse of stiffness is flexibility.

Elasticity: The ability of a material to return to its original geometryafter deformation.

Viscous: The ability of a material to resist flow.

Visco-elasticity: The ability of a material to display both elastic andviscous behaviour in deformation.

Yield: The situation when a material can no longer return back to itsoriginal geometry after deformation.

4.7.1.3 Structural Elements

Thin structures:

-   -   a. Beams,    -   b. Membranes, Plates & Shells

Thick structures: Solids

Shell: A shell will be taken to mean a curved, relatively thin structurehaving bending, tensile and compressive stiffness. For example, a curvedstructural wall of a mask may be a shell. In some forms, a shell may befaceted. In some forms a shell may be airtight. In some forms a shellmay not be airtight.

Membrane: Membrane will be taken to mean a typically thin element thathas, preferably, substantially no resistance to bending, but hasresistance to being stretched.

Load transfer member: A structural member which transfers load from onelocation to another member.

Load support member: A structural member which transfers load from onelocation to a non-structural item, such as the face.

Tension member: A structural element that resists tensional forces

Tie (noun): A structure designed to resist tension.

Compression member: A structural element that resists compressionforces.

Strut: A strut will be taken to be a structural component designed toincrease the compression resistance of another component in at least onedirection.

Stiffener

Stiffener: A stiffener will be taken to mean a structural componentdesigned to increase the bending resistance of another component in atleast one direction.

Elbow: An elbow is an example of a structure that directs an axis offlow of air travelling therethrough to change direction through anangle. In one form, the angle may be approximately 90 degrees. Inanother form, the angle may be more, or less than 90 degrees. The elbowmay have an approximately circular cross-section. In another form theelbow may have an oval or a rectangular cross-section. In certain formsan elbow may be rotatable with respect to a mating component, e.g. about360 degrees. In certain forms an elbow may be removable from a matingcomponent, e.g. via a snap connection. In certain forms, an elbow may beassembled to a mating component via a one-time snap during manufacture,but not removable by a patient.

Frame: Frame will be taken to mean a mask structure that bears the loadof tension between two or more points of connection with a headgear. Amask frame may be a non-airtight load bearing structure in the mask.However, some forms of mask frame may also be air-tight.

Seal: May be a noun form (“a seal”) which refers to a structure, or averb form (“to seal”) which refers to the effect. Two elements may beconstructed and/or arranged to ‘seal’ or to effect ‘sealing’therebetween without requiring a separate ‘seal’ element per se.

Swivel (noun): A subassembly of components configured to rotate about acommon axis, preferably independently, preferably under low torque. Inone form, the swivel may be constructed to rotate through an angle of atleast 360 degrees. In another form, the swivel may be constructed torotate through an angle less than 360 degrees. When used in the contextof an air delivery conduit, the sub-assembly of components preferablycomprises a matched pair of cylindrical conduits. There may be little orno leak flow of air from the swivel in use.

4.7.2 Respiratory Cycle

Apnea: According to some definitions, an apnea is said to have occurredwhen flow falls below a predetermined threshold for a duration, e.g. 10seconds. An obstructive apnea will be said to have occurred when,despite patient effort, some obstruction of the airway does not allowair to flow. A central apnea will be said to have occurred when an apneais detected that is due to a reduction in breathing effort, or theabsence of breathing effort, despite the airway being patent. A mixedapnea occurs when a reduction or absence of breathing effort coincideswith an obstructed airway.

Breathing rate: The rate of spontaneous respiration of a patient,usually measured in breaths per minute.

Duty cycle: The ratio of inhalation time, Ti to total breath time, Ttot.

Effort (breathing): The work done by a spontaneously breathing personattempting to breathe.

Expiratory portion of a breathing cycle: The period from the start ofexpiratory flow to the start of inspiratory flow.

Flow limitation: Flow limitation will be taken to be the state ofaffairs in a patient's respiration where an increase in effort by thepatient does not give rise to a corresponding increase in flow. Whereflow limitation occurs during an inspiratory portion of the breathingcycle it may be described as inspiratory flow limitation. Where flowlimitation occurs during an expiratory portion of the breathing cycle itmay be described as expiratory flow limitation.

Types of flow limited inspiratory waveforms:

(i) Flattened: Having a rise followed by a relatively flat portion,followed by a fall.

(ii) M-shaped: Having two local peaks, one at the leading edge, and oneat the trailing edge, and a relatively flat portion between the twopeaks.

(iii) Chair-shaped: Having a single local peak, the peak being at theleading edge, followed by a relatively flat portion.

(iv) Reverse-chair shaped: Having a relatively flat portion followed bysingle local peak, the peak being at the trailing edge.

Hypopnea: According to some definitions, a hypopnea is taken to be areduction in flow, but not a cessation of flow. In one form, a hypopneamay be said to have occurred when there is a reduction in flow below athreshold rate for a duration. A central hypopnea will be said to haveoccurred when a hypopnea is detected that is due to a reduction inbreathing effort. In one form in adults, either of the following may beregarded as being hypopneas:

-   -   (i) a 30% reduction in patient breathing for at least 10 seconds        plus an associated 4% desaturation; or    -   (ii) a reduction in patient breathing (but less than 50%) for at        least 10 seconds, with an associated desaturation of at least 3%        or an arousal.

Hyperpnea: An increase in flow to a level higher than normal.

Inspiratory portion of a breathing cycle: The period from the start ofinspiratory flow to the start of expiratory flow will be taken to be theinspiratory portion of a breathing cycle.

Patency (airway): The degree of the airway being open, or the extent towhich the airway is open. A patent airway is open. Airway patency may bequantified, for example with a value of one (1) being patent, and avalue of zero (0), being closed (obstructed).

Positive End-Expiratory Pressure (PEEP): The pressure above atmospherein the lungs that exists at the end of expiration.

Peak flow rate (Qpeak): The maximum value of flow rate during theinspiratory portion of the respiratory flow waveform.

Respiratory flow rate, patient airflow rate, respiratory airflow rate(Qr): These terms may be understood to refer to the RPT device'sestimate of respiratory flow rate, as opposed to “true respiratory flowrate” or “true respiratory flow rate”, which is the actual respiratoryflow rate experienced by the patient, usually expressed in litres perminute.

Tidal volume (Vt): The volume of air inhaled or exhaled during normalbreathing, when extra effort is not applied. In principle theinspiratory volume Vi (the volume of air inhaled) is equal to theexpiratory volume Ve (the volume of air exhaled), and therefore a singletidal volume Vt may be defined as equal to either quantity. In practicethe tidal volume Vt is estimated as some combination, e.g. the mean, ofthe inspiratory volume Vi and the expiratory volume Ve.

Inhalation Time (Ti): The duration of the inspiratory portion of therespiratory flow rate waveform.

Exhalation Time (Te): The duration of the expiratory portion of therespiratory flow rate waveform.

Total Time (Ttot): The total duration between the start of oneinspiratory portion of a respiratory flow rate waveform and the start ofthe following inspiratory portion of the respiratory flow rate waveform.

Typical recent ventilation: The value of ventilation around which recentvalues of ventilation Vent over some predetermined timescale tend tocluster, that is, a measure of the central tendency of the recent valuesof ventilation.

Upper airway obstruction (UAO): includes both partial and total upperairway obstruction. This may be associated with a state of flowlimitation, in which the flow rate increases only slightly or may evendecrease as the pressure difference across the upper airway increases(Starling resistor behaviour).

Ventilation (Vent): A measure of a rate of gas being exchanged by thepatient's respiratory system. Measures of ventilation may include one orboth of inspiratory and expiratory flow, per unit time. When expressedas a volume per minute, this quantity is often referred to as “minuteventilation”. Minute ventilation is sometimes given simply as a volume,understood to be the volume per minute.

4.7.3 Ventilation

Adaptive Servo-Ventilator (ASV): A servo-ventilator that has achangeable, rather than fixed target ventilation. The changeable targetventilation may be learned from some characteristic of the patient, forexample, a respiratory characteristic of the patient.

Backup rate: A parameter of a ventilator that establishes the minimumbreathing rate (typically in number of breaths per minute) that theventilator will deliver to the patient, if not triggered by spontaneousrespiratory effort.

Cycled: The termination of a ventilator's inspiratory phase. When aventilator delivers a breath to a spontaneously breathing patient, atthe end of the inspiratory portion of the breathing cycle, theventilator is said to be cycled to stop delivering the breath.

Expiratory positive airway pressure (EPAP): a base pressure, to which apressure varying within the breath is added to produce the desiredinterface pressure which the ventilator will attempt to achieve at agiven time.

End expiratory pressure (EEP): Desired interface pressure which theventilator will attempt to achieve at the end of the expiratory portionof the breath. If the pressure waveform template Π(Φ) is zero-valued atthe end of expiration, i.e. Π(Φ)=0 when Φ=1, the EEP is equal to theEPAP.

Inspiratory positive airway pressure (IPAP): Maximum desired interfacepressure which the ventilator will attempt to achieve during theinspiratory portion of the breath.

Pressure support: A number that is indicative of the increase inpressure during ventilator inspiration over that during ventilatorexpiration, and generally means the difference in pressure between themaximum value during inspiration and the base pressure (e.g.,PS=IPAP−EPAP). In some contexts, pressure support means the differencewhich the ventilator aims to achieve, rather than what it actuallyachieves.

Servo-ventilator: A ventilator that measures patient ventilation, has atarget ventilation, and which adjusts the level of pressure support tobring the patient ventilation towards the target ventilation.

Spontaneous/Timed (S/T): A mode of a ventilator or other device thatattempts to detect the initiation of a breath of a spontaneouslybreathing patient. If however, the device is unable to detect a breathwithin a predetermined period of time, the device will automaticallyinitiate delivery of the breath.

Swing: Equivalent term to pressure support.

Triggered: When a ventilator, or other respiratory therapy device suchas an RPT device or portable oxygen concentrator, delivers a volume ofbreathable gas to a spontaneously breathing patient, it is said to betriggered to do so. Triggering usually takes place at or near theinitiation of the respiratory portion of the breathing cycle by thepatient's efforts.

4.7.4 Anatomy 4.7.4.1 Anatomy of the Face

Ala: the external outer wall or “wing” of each nostril (plural: alar)

Alar angle:

Alare: The most lateral point on the nasal ala.

Alar curvature (or alar crest) point: The most posterior point in thecurved base line of each ala, found in the crease formed by the union ofthe ala with the cheek.

Auricle: The whole external visible part of the ear.

(nose) Bony framework: The bony framework of the nose comprises thenasal bones, the frontal process of the maxillae and the nasal part ofthe frontal bone.

(nose) Cartilaginous framework: The cartilaginous framework of the nosecomprises the septal, lateral, major and minor cartilages.

Columella: the strip of skin that separates the nares and which runsfrom the pronasale to the upper lip.

Columella angle: The angle between the line drawn through the midpointof the nostril aperture and a line drawn perpendicular to the Frankforthorizontal while intersecting subnasale.

Frankfort horizontal plane: A line extending from the most inferiorpoint of the orbital margin to the left tragion. The tragion is thedeepest point in the notch superior to the tragus of the auricle.

Glabella: Located on the soft tissue, the most prominent point in themidsagittal plane of the forehead.

Lateral nasal cartilage: A generally triangular plate of cartilage. Itssuperior margin is attached to the nasal bone and frontal process of themaxilla, and its inferior margin is connected to the greater alarcartilage.

Lip, lower (labrale inferius):

Lip, upper (labrale superius):

Greater alar cartilage: A plate of cartilage lying below the lateralnasal cartilage. It is curved around the anterior part of the naris. Itsposterior end is connected to the frontal process of the maxilla by atough fibrous membrane containing three or four minor cartilages of theala.

Nares (Nostrils): Approximately ellipsoidal apertures forming theentrance to the nasal cavity. The singular form of nares is naris(nostril). The nares are separated by the nasal septum.

Naso-labial sulcus or Naso-labial fold: The skin fold or groove thatruns from each side of the nose to the corners of the mouth, separatingthe cheeks from the upper lip.

Naso-labial angle: The angle between the columella and the upper lip,while intersecting subnasale.

Otobasion inferior: The lowest point of attachment of the auricle to theskin of the face.

Otobasion superior: The highest point of attachment of the auricle tothe skin of the face.

Pronasale: the most protruded point or tip of the nose, which can beidentified in lateral view of the rest of the portion of the head.

Philtrum: the midline groove that runs from lower border of the nasalseptum to the top of the lip in the upper lip region.

Pogonion: Located on the soft tissue, the most anterior midpoint of thechin.

Ridge (nasal): The nasal ridge is the midline prominence of the nose,extending from the Sellion to the Pronasale.

Sagittal plane: A vertical plane that passes from anterior (front) toposterior (rear). The midsagittal plane is a sagittal plane that dividesthe body into right and left halves.

Sellion: Located on the soft tissue, the most concave point overlyingthe area of the frontonasal suture.

Septal cartilage (nasal): The nasal septal cartilage forms part of theseptum and divides the front part of the nasal cavity.

Subalare: The point at the lower margin of the alar base, where the alarbase joins with the skin of the superior (upper) lip.

Subnasal point: Located on the soft tissue, the point at which thecolumella merges with the upper lip in the midsagittal plane.

Supramenton: The point of greatest concavity in the midline of the lowerlip between labrale inferius and soft tissue pogonion

4.7.4.2 Anatomy of the Skull

Frontal bone: The frontal bone includes a large vertical portion, thesquama frontalis, corresponding to the region known as the forehead.

Mandible: The mandible forms the lower jaw. The mental protuberance isthe bony protuberance of the jaw that forms the chin.

Maxilla: The maxilla forms the upper jaw and is located above themandible and below the orbits. The frontal process of the maxillaprojects upwards by the side of the nose, and forms part of its lateralboundary.

Nasal bones: The nasal bones are two small oblong bones, varying in sizeand form in different individuals; they are placed side by side at themiddle and upper part of the face, and form, by their junction, the“bridge” of the nose.

Nasion: The intersection of the frontal bone and the two nasal bones, adepressed area directly between the eyes and superior to the bridge ofthe nose.

Occipital bone: The occipital bone is situated at the back and lowerpart of the cranium. It includes an oval aperture, the foramen magnum,through which the cranial cavity communicates with the vertebral canal.The curved plate behind the foramen magnum is the squama occipitalis.

Orbit: The bony cavity in the skull to contain the eyeball.

Parietal bones: The parietal bones are the bones that, when joinedtogether, form the roof and sides of the cranium.

Temporal bones: The temporal bones are situated on the bases and sidesof the skull, and support that part of the face known as the temple.

Zygomatic bones: The face includes two zygomatic bones, located in theupper and lateral parts of the face and forming the prominence of thecheek.

4.7.4.3 Anatomy of the Respiratory System

Diaphragm: A sheet of muscle that extends across the bottom of the ribcage. The diaphragm separates the thoracic cavity, containing the heart,lungs and ribs, from the abdominal cavity. As the diaphragm contractsthe volume of the thoracic cavity increases and air is drawn into thelungs.

Larynx: The larynx, or voice box houses the vocal folds and connects theinferior part of the pharynx (hypopharynx) with the trachea.

Lungs: The organs of respiration in humans. The conducting zone of thelungs contains the trachea, the bronchi, the bronchioles, and theterminal bronchioles. The respiratory zone contains the respiratorybronchioles, the alveolar ducts, and the alveoli.

Nasal cavity: The nasal cavity (or nasal fossa) is a large air filledspace above and behind the nose in the middle of the face. The nasalcavity is divided in two by a vertical fin called the nasal septum. Onthe sides of the nasal cavity are three horizontal outgrowths callednasal conchae (singular “concha”) or turbinates. To the front of thenasal cavity is the nose, while the back blends, via the choanae, intothe nasopharynx.

Pharynx: The part of the throat situated immediately inferior to (below)the nasal cavity, and superior to the oesophagus and larynx. The pharynxis conventionally divided into three sections: the nasopharynx(epipharynx) (the nasal part of the pharynx), the oropharynx(mesopharynx) (the oral part of the pharynx), and the laryngopharynx(hypopharynx).

4.7.5 Patient Interface

Anti-asphyxia valve (AAV): The component or sub-assembly of a masksystem that, by opening to atmosphere in a failsafe manner, reduces therisk of excessive CO2 rebreathing by a patient.

Functional dead space: (description to be inserted here)

Headgear: Headgear will be taken to mean a form of positioning andstabilizing structure designed to hold a device, e.g. a mask, on a head.

Plenum chamber: a mask plenum chamber will be taken to mean a portion ofa patient interface having walls at least partially enclosing a volumeof space, the volume having air therein pressurised above atmosphericpressure in use. A shell may form part of the walls of a mask plenumchamber.

Vent: (noun): A structure that allows a flow of air from an interior ofthe mask, or conduit, to ambient air for clinically effective washout ofexhaled gases. For example, a clinically effective washout may involve aflow rate of about 10 litres per minute to about 100 litres per minute,depending on the mask design and treatment pressure.

4.7.6 Shape of Structures

Products in accordance with the present technology may comprise one ormore three-dimensional mechanical structures, for example a mask cushionor an impeller. The three-dimensional structures may be bounded bytwo-dimensional surfaces. These surfaces may be distinguished using alabel to describe an associated surface orientation, location, function,or some other characteristic. For example a structure may comprise oneor more of an anterior surface, a posterior surface, an interior surfaceand an exterior surface. In another example, a seal-forming structuremay comprise a face-contacting (e.g. outer) surface, and a separatenon-face-contacting (e.g. underside or inner) surface. In anotherexample, a structure may comprise a first surface and a second surface.

To facilitate describing the shape of the three-dimensional structuresand the surfaces, we first consider a cross-section through a surface ofthe structure at a point, p. See FIG. 3B to FIG. 3F, which illustrateexamples of cross-sections at point p on a surface, and the resultingplane curves. FIGS. 3B to 3F also illustrate an outward normal vector atp. The outward normal vector at p points away from the surface. In someexamples we describe the surface from the point of view of an imaginarysmall person standing upright on the surface.

4.7.6.1 Curvature in One Dimension

The curvature of a plane curve at p may be described as having a sign(e.g. positive, negative) and a magnitude (e.g. 1/radius of a circlethat just touches the curve at p).

Positive curvature: If the curve at p turns towards the outward normal,the curvature at that point will be taken to be positive (if theimaginary small person leaves the point p they must walk uphill). SeeFIG. 3B (relatively large positive curvature compared to FIG. 3C) andFIG. 3C (relatively small positive curvature compared to FIG. 3B). Suchcurves are often referred to as concave.

Zero curvature: If the curve at p is a straight line, the curvature willbe taken to be zero (if the imaginary small person leaves the point p,they can walk on a level, neither up nor down). See FIG. 3D.

Negative curvature: If the curve at p turns away from the outwardnormal, the curvature in that direction at that point will be taken tobe negative (if the imaginary small person leaves the point p they mustwalk downhill) See FIG. 3E (relatively small negative curvature comparedto FIG. 3F) and FIG. 3F (relatively large negative curvature compared toFIG. 3E). Such curves are often referred to as convex.

4.7.6.2 Curvature of Two Dimensional Surfaces

A description of the shape at a given point on a two-dimensional surfacein accordance with the present technology may include multiple normalcross-sections. The multiple cross-sections may cut the surface in aplane that includes the outward normal (a “normal plane”), and eachcross-section may be taken in a different direction. Each cross-sectionresults in a plane curve with a corresponding curvature. The differentcurvatures at that point may have the same sign, or a different sign.Each of the curvatures at that point has a magnitude, e.g. relativelysmall. The plane curves in FIGS. 3B to 3F could be examples of suchmultiple cross-sections at a particular point.

Principal curvatures and directions: The directions of the normal planeswhere the curvature of the curve takes its maximum and minimum valuesare called the principal directions. In the examples of FIG. 3B to FIG.3F, the maximum curvature occurs in FIG. 3B, and the minimum occurs inFIG. 3F, hence FIG. 3B and FIG. 3F are cross sections in the principaldirections. The principal curvatures at p are the curvatures in theprincipal directions.

Region of a surface: A connected set of points on a surface. The set ofpoints in a region may have similar characteristics, e.g. curvatures orsigns.

Saddle region: A region where at each point, the principal curvatureshave opposite signs, that is, one is positive, and the other is negative(depending on the direction to which the imaginary person turns, theymay walk uphill or downhill).

Dome region: A region where at each point the principal curvatures havethe same sign, e.g. both positive (a “concave dome”) or both negative (a“convex dome”).

Cylindrical region: A region where one principal curvature is zero (or,for example, zero within manufacturing tolerances) and the otherprincipal curvature is non-zero.

Planar region: A region of a surface where both of the principalcurvatures are zero (or, for example, zero within manufacturingtolerances).

Edge of a surface: A boundary or limit of a surface or region.

Path: In certain forms of the present technology, ‘path’ will be takento mean a path in the mathematical—topological sense, e.g. a continuousspace curve from f(0) to f(1) on a surface. In certain forms of thepresent technology, a ‘path’ may be described as a route or course,including e.g. a set of points on a surface. (The path for the imaginaryperson is where they walk on the surface, and is analogous to a gardenpath).

Path length: In certain forms of the present technology, ‘path length’will be taken to mean the distance along the surface from f(0) to f(1),that is, the distance along the path on the surface. There may be morethan one path between two points on a surface and such paths may havedifferent path lengths. (The path length for the imaginary person wouldbe the distance they have to walk on the surface along the path).

Straight-line distance: The straight-line distance is the distancebetween two points on a surface, but without regard to the surface. Onplanar regions, there would be a path on the surface having the samepath length as the straight-line distance between two points on thesurface. On non-planar surfaces, there may be no paths having the samepath length as the straight-line distance between two points. (For theimaginary person, the straight-line distance would correspond to thedistance ‘as the crow flies’.)

4.7.6.3 Space Curves

Space curves: Unlike a plane curve, a space curve does not necessarilylie in any particular plane. A space curve may be closed, that is,having no endpoints. A space curve may be considered to be aone-dimensional piece of three-dimensional space. An imaginary personwalking on a strand of the DNA helix walks along a space curve. Atypical human left ear comprises a helix, which is a left-hand helix,see FIG. 3Q. A typical human right ear comprises a helix, which is aright-hand helix, see FIG. 3R. FIG. 3S shows a right-hand helix. Theedge of a structure, e.g. the edge of a membrane or impeller, may followa space curve. In general, a space curve may be described by a curvatureand a torsion at each point on the space curve. Torsion is a measure ofhow the curve turns out of a plane. Torsion has a sign and a magnitude.The torsion at a point on a space curve may be characterised withreference to the tangent, normal and binormal vectors at that point.

Tangent unit vector (or unit tangent vector): For each point on a curve,a vector at the point specifies a direction from that point, as well asa magnitude. A tangent unit vector is a unit vector pointing in the samedirection as the curve at that point. If an imaginary person were flyingalong the curve and fell off her vehicle at a particular point, thedirection of the tangent vector is the direction she would betravelling.

Unit normal vector: As the imaginary person moves along the curve, thistangent vector itself changes. The unit vector pointing in the samedirection that the tangent vector is changing is called the unitprincipal normal vector. It is perpendicular to the tangent vector.

Binormal unit vector: The binormal unit vector is perpendicular to boththe tangent vector and the principal normal vector. Its direction may bedetermined by a right-hand rule (see e.g. FIG. 3P), or alternatively bya left-hand rule (FIG. 3O).

Osculating plane: The plane containing the unit tangent vector and theunit principal normal vector. See FIGS. 3O and 3P.

Torsion of a space curve: The torsion at a point of a space curve is themagnitude of the rate of change of the binormal unit vector at thatpoint. It measures how much the curve deviates from the osculatingplane. A space curve which lies in a plane has zero torsion. A spacecurve which deviates a relatively small amount from the osculating planewill have a relatively small magnitude of torsion (e.g. a gently slopinghelical path). A space curve which deviates a relatively large amountfrom the osculating plane will have a relatively large magnitude oftorsion (e.g. a steeply sloping helical path). With reference to FIG.3S, since T2>T1, the magnitude of the torsion near the top coils of thehelix of FIG. 3S is greater than the magnitude of the torsion of thebottom coils of the helix of FIG. 3S

With reference to the right-hand rule of FIG. 3P, a space curve turningtowards the direction of the right-hand binormal may be considered ashaving a right-hand positive torsion (e.g. a right-hand helix as shownin FIG. 3S). A space curve turning away from the direction of theright-hand binormal may be considered as having a right-hand negativetorsion (e.g. a left-hand helix).

Equivalently, and with reference to a left-hand rule (see FIG. 3O), aspace curve turning towards the direction of the left-hand binormal maybe considered as having a left-hand positive torsion (e.g. a left-handhelix). Hence left-hand positive is equivalent to right-hand negative.See FIG. 3T.

4.7.6.4 Holes

A surface may have a one-dimensional hole, e.g. a hole bounded by aplane curve or by a space curve. Thin structures (e.g. a membrane) witha hole, may be described as having a one-dimensional hole. See forexample the one dimensional hole in the surface of structure shown inFIG. 3I, bounded by a plane curve.

A structure may have a two-dimensional hole, e.g. a hole bounded by asurface. For example, an inflatable tyre has a two dimensional holebounded by the interior surface of the tyre. In another example, abladder with a cavity for air or gel could have a two-dimensional hole.See for example the cushion of FIG. 3L and the example cross-sectionstherethrough in FIG. 3M and FIG. 3N, with the interior surface boundinga two dimensional hole indicated. In a yet another example, a conduitmay comprise a one-dimension hole (e.g. at its entrance or at its exit),and a two-dimension hole bounded by the inside surface of the conduit.See also the two dimensional hole through the structure shown in FIG.3K, bounded by a surface as shown.

4.8 Other Remarks

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in Patent Office patent files orrecords, but otherwise reserves all copyright rights whatsoever.

Unless the context clearly dictates otherwise and where a range ofvalues is provided, it is understood that each intervening value, to thetenth of the unit of the lower limit, between the upper and lower limitof that range, and any other stated or intervening value in that statedrange is encompassed within the technology. The upper and lower limitsof these intervening ranges, which may be independently included in theintervening ranges, are also encompassed within the technology, subjectto any specifically excluded limit in the stated range. Where the statedrange includes one or both of the limits, ranges excluding either orboth of those included limits are also included in the technology.

Furthermore, where a value or values are stated herein as beingimplemented as part of the technology, it is understood that such valuesmay be approximated, unless otherwise stated, and such values may beutilized to any suitable significant digit to the extent that apractical technical implementation may permit or require it.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this technology belongs. Although any methods andmaterials similar or equivalent to those described herein can also beused in the practice or testing of the present technology, a limitednumber of the exemplary methods and materials are described herein.

When a particular material is identified as being used to construct acomponent, obvious alternative materials with similar properties may beused as a substitute. Furthermore, unless specified to the contrary, anyand all components herein described are understood to be capable ofbeing manufactured and, as such, may be manufactured together orseparately.

It must be noted that as used herein and in the appended claims, thesingular forms “a”, “an”, and “the” include their plural equivalents,unless the context clearly dictates otherwise.

All publications mentioned herein are incorporated herein by referencein their entirety to disclose and describe the methods and/or materialswhich are the subject of those publications. The publications discussedherein are provided solely for their disclosure prior to the filing dateof the present application. Nothing herein is to be construed as anadmission that the present technology is not entitled to antedate suchpublication by virtue of prior invention. Further, the dates ofpublication provided may be different from the actual publication dates,which may need to be independently confirmed.

The terms “comprises” and “comprising” should be interpreted asreferring to elements, components, or steps in a non-exclusive manner,indicating that the referenced elements, components, or steps may bepresent, or utilized, or combined with other elements, components, orsteps that are not expressly referenced.

The subject headings used in the detailed description are included onlyfor the ease of reference of the reader and should not be used to limitthe subject matter found throughout the disclosure or the claims. Thesubject headings should not be used in construing the scope of theclaims or the claim limitations.

Although the technology herein has been described with reference toparticular examples, it is to be understood that these examples aremerely illustrative of the principles and applications of thetechnology. In some instances, the terminology and symbols may implyspecific details that are not required to practice the technology. Forexample, although the terms “first” and “second” may be used, unlessotherwise specified, they are not intended to indicate any order but maybe utilised to distinguish between distinct elements. Furthermore,although process steps in the methodologies may be described orillustrated in an order, such an ordering is not required. Those skilledin the art will recognize that such ordering may be modified and/oraspects thereof may be conducted concurrently or even synchronously.

It is therefore to be understood that numerous modifications may be madeto the illustrative examples and that other arrangements may be devisedwithout departing from the spirit and scope of the technology.

4.9 REFERENCE SIGNS LIST patient 1000 bed partner 1100 main body 2405patient interface 3000 main body 3010 seal - forming structure 3100mouth portion 3105 oral portion 3105 nasal portion 3110 first opening3115 second opening 3120 third opening 3125 receptacle 3130 base 3135one side wall 3140 outer rim 3145 pace 3150 fourth opening 3155 nasalbase 3160 nasal pillow 3165 nasal plenum 3170 inlet opening 3175 flange3180 side wall 3182 first side 3185 second side 3190 line 3195 flange3197 plenum 3200 chord 3210 wall 3211 superior point 3220 upper headgearconnectors 3221 inferior point 3230 lower headgear connectors 3231structure 3300 strap 3310 tube 3350 non - extendable tube section 3363vent 3400 main body 3405 cover 3410 diffuser 3415 frame 3420 receptacle3425 first flange 3430 second flange 3435 channel 3440 gaps 3445 tab3450 vent wall 3455 vent hole 3460 side walls 3465 anchor block 3470surface 3475 anchor hole 3480 anchor peg 3485 first support strip 3490second support strips 3495 gap 3497 channel 3498 Projection 3499connection port 3600 elbow 3610 forehead support 3700 ISO 3744 patientinterface 3800 RPT device 4000 external housing 4010 upper portion 4012portion 4014 panel s 4015 chassis 4016 handle 4018 pneumatic block 4020air filter 4110 inlet air filter 4112 outlet air filter 4114 muffler4120 inlet muffler 4122 outlet muffler 4124 pressure generator 4140blower 4142 motor 4144 anti - spill back valve 4160 air circuit 4170electrical components 4200 PCBA 4202 electrical power supply 4210 inputdevices 4220 central controller 4230 therapy device controller 4240protection circuits 4250 memory 4260 transducers 4270 pressure sensors4272 flow rate sensors 4274 data communication interface 4280 remoteexternal communication network 4282 local external communication network4284 remote external device 4286 local external device 4288 outputdevices 4290 algorithms 4300 therapy engine module 4320 therapy controlmodule 4330 humidifier 5000 humidifier inlet 5002 humidifier outlet 5004humidifier base 5006 reservoir 5110 conductive portion 5120 humidifierreservoir dock 5130 locking lever 5135 water level indicator 5150heating element 5240 clip 6000 lumen 6005 central longitudinal axis 6007middle flange 6010 first end flange 6015 flange 6020 first channel 6025second channel 6030 first side 6035 second side 6040 side wall 6047channel side 6050 wing 6060 nasal pillow facing side 6065 base 6070 end6075 nasal module magnet 7000 receptacle magnet 7005 lip seal 7010 core7015 core 7016 silicone rubber covering 7020 indicia 8000 indicia 8005indentation 8010 tab 8015 nasal prongs 3810a nasal prongs 3810b lumens3820a lumens 3820b

1. A patient interface comprising: a mouth plenum pressurisable to atherapeutic pressure of at least 6 cmH₂O above ambient air pressure,said mouth plenum including a plenum chamber inlet port sized andstructured to receive a flow of air at the therapeutic pressure forbreathing by a patient, a seal-forming structure constructed andarranged to form a seal with a region of the patient's face surroundingan entrance to the patient's airways, said seal-forming structure havinga hole therein such that the flow of air at said therapeutic pressure isdelivered to at least an entrance to the patient's nares, theseal-forming structure constructed and arranged to maintain saidtherapeutic pressure in the plenum chamber throughout the patient'srespiratory cycle in use, the seal-forming structure comprising: a mouthportion that forms at least part of the mouth plenum and is configuredto seal around the patient's mouth; and a nasal portion that isconfigured to seal with the patient's nares, the nasal portioncomprising a nasal plenum with an inlet opening, the nasal plenum beingconfigured to be received within the receptacle; a positioning andstabilising structure to provide a force to hold the seal-formingstructure in a therapeutically effective position on the patient's head;and a vent structure to allow a continuous flow of gases exhaled by thepatient from an interior of the plenum chamber to ambient, said ventstructure being sized and shaped to maintain the therapeutic pressure inthe plenum chamber in use, the vent structure comprising: a main bodyconfigured to be secured to the mouth portion, the main body comprisinga vent wall with a plurality of vent holes, a receptacle, and a pair ofanchor sockets located on opposing lateral sides of the receptacle; acover comprising a pair of anchor pegs on lateral sides of the cover,the anchor pegs being configured to be inserted into the anchor socketsto secure the cover to the main body; and a diffuser received within thereceptacle between the anchor sockets, the diffuser being sandwichedbetween the main body and the cover, wherein the patient interface isconfigured to allow the patient to breathe from ambient through theirmouth in the absence of a flow of pressurised air through the plenumchamber inlet port.
 2. The patient interface of claim 1, wherein theanchor sockets are keyed with the anchor pegs so that only anchor pegswith the same shape as the anchor sockets are receivable within theanchor sockets.
 3. The patient interface of claim 1, wherein the anchorsockets are tapered so that the anchor pegs become wedged in the anchorsockets when the cover is secured to the main body.
 4. The patientinterface of claim 1, wherein the main body comprises a first flange anda second flange that forms a channel with the first flange, wherein themouth portion comprises a vent opening and a rim of the vent opening isreceived in the channel when the main body is secured to the mouthportion.
 5. The patient interface of claim 4, wherein the anchor socketsextend deeper than the channel.
 6. The patient interface of claim 1,wherein the vent wall encloses an end of the receptacle that is closestto the interior of the mouth plenum.
 7. The patient interface of claim1, wherein the diffuser is spaced apart from the vent holes.
 8. Thepatient interface of claim 1, wherein each anchor socket has a differentsize.
 9. The patient interface of claim 1, wherein each anchor sockethas a different shape.
 10. The patient interface of claim 1, wherein theanchor sockets are configured to prevent the cover from being secured tothe main body in the wrong orientation.
 11. The patient interface ofclaim 1, wherein a perimeter of the cover is smaller than a perimeter ofthe main body so that a gap is formed between the main body and thecover when the cover is secured to the main body.
 12. The patientinterface of claim 1, wherein the vent holes are tapered so that thevent holes narrow in a direction toward the diffuser.
 13. The patientinterface of claim 12, wherein opposing sides of the interior wall ofeach vent hole forms an angle of taper 10 to 35 degrees.
 14. The patientinterface of claim 13, wherein the angle of taper is about 10 degrees.15. The patient interface of claim 13, wherein the angle of taper isabout 35 degrees.
 16. The patient interface of claim 1, wherein a baseof each vent hole is flared.
 17. The patient interface of claim 16,wherein the flared portion of the vent hole has a radius of curvature of0.2 mm to 0.4 mm.
 18. The patient interface of claim 17, wherein theradius of curvature is about 0.25 mm.
 19. The patient interface of claim17, wherein the radius of curvature is about 0.3 mm.
 20. The patientinterface of claim 1, wherein a smallest diameter of each vent hole is0.5 mm to 2.0 mm.
 21. The patient interface of claim 20, wherein thesmallest diameter is 0.89 mm.
 22. The patient interface of claim 20,wherein the smallest diameter is 0.98 mm.
 23. The patient interface ofclaim 20, wherein the smallest diameter is 1.01 mm.
 24. The patientinterface of claim 20, wherein the smallest diameter is 1.17 mm.
 25. Arespiratory therapy system comprising: the patient interface of claim 1;a respiratory pressure therapy device configured to generate the flow ofair at the therapeutic pressure; and an air circuit configured to directthe flow of air at the therapeutic pressure from the respiratorypressure therapy device to the patient interface.
 26. A patientinterface comprising: a mouth plenum pressurisable to a therapeuticpressure of at least 6 cmH₂O above ambient air pressure, said mouthplenum including a plenum chamber inlet port sized and structured toreceive a flow of air at the therapeutic pressure for breathing by apatient, a seal-forming structure constructed and arranged to form aseal with a region of the patient's face surrounding an entrance to thepatient's airways, said seal-forming structure having a hole thereinsuch that the flow of air at said therapeutic pressure is delivered toat least an entrance to the patient's nares, the seal-forming structureconstructed and arranged to maintain said therapeutic pressure in theplenum chamber throughout the patient's respiratory cycle in use, theseal-forming structure comprising: a mouth portion that forms at leastpart of the mouth plenum and is configured to seal around the patient'smouth; and a nasal portion that is configured to seal with the patient'snares, the nasal portion comprising a nasal plenum with an inletopening, the nasal plenum being configured to be received within thereceptacle; a positioning and stabilising structure to provide a forceto hold the seal-forming structure in a therapeutically effectiveposition on the patient's head; and a vent structure to allow acontinuous flow of gases exhaled by the patient from an interior of theplenum chamber to ambient, said vent structure being sized and shaped tomaintain the therapeutic pressure in the plenum chamber in use, the ventstructure comprising: a vent wall with a plurality of vent openings anda trough on an outwardly facing surface that completely encircles thevent openings; at least one side wall extending from the vent wall; anda flange extending from an end of the at least one side wall so that anedge of the vent wall, an outer surface of the at least one side wall,and the flange together form a channel configured to receive a rimaround the vent opening in the mouth portion, the flange beingconfigured to be received inside the mouth plenum, wherein the patientinterface is configured to allow the patient to breathe from ambientthrough their mouth in the absence of a flow of pressurised air throughthe plenum chamber inlet port.
 27. The patient interface of claim 26,wherein the outwardly facing surface of the vent wall is convex and aninwardly facing surface of the vent wall opposite the outwardly facingsurface is convex.
 28. The patient interface of claim 26, wherein thevent holes are tapered so that the vent holes narrow in a directiontoward the outwardly facing surface of the vent wall.
 29. A respiratorytherapy system comprising: the patient interface of claim 26; arespiratory pressure therapy device configured to generate the flow ofair at the therapeutic pressure; and an air circuit configured to directthe flow of air at the therapeutic pressure from the respiratorypressure therapy device to the patient interface.